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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water .
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why ca n't we make water in laboratories by combining hydrogen and oxygen ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
|
in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it .
|
what is a polar molecule ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
|
start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water .
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do paper towels soak up water only because the adhesion is really high , or are there other properties why they can do that ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth .
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in what is a `` solvent '' ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form .
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is there a root word for covalent bonds ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying .
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given the partial positive charge on both hydrogen atoms in the water molecule would n't it makes sense for them repel each other and end with more energy efficient configuration of straight line bond configuration rather than v-shape which would have both of them bunched together ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw .
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can anyone else explain more in depth what causes adhesion and cohesion ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion .
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what was capillary action again ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge .
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why is h2o is a v-shape bond ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land .
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how did life form in the first place ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish .
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does that mean in conditions without gravity water would fill the straw completely , because there are no forces that can stop this process ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds .
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do negative charges in an atom occur when the atom has or requires more electrons ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion .
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are there any other molecules like water that expand when cooled ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying .
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given that a floating block of ice displaces the same amount of surrounding liquid water as it does when melted , surely if the ice at the north pole sank , it would have to be denser than liquid water , thus having a smaller volume and ( the immediate effect ) would be for sea levels to fall ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar .
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at 4 ; 42 - what is the strongest acid ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way .
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in other words , why do the positive hydrogens not blow each other apart ( like charges repel ) to form a molecule in the shape of a straight line , where the two hydrogens are opposite from each other ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water .
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if water is made up of hydrogen and oxygen both of which are hight flamable , why ca n't you burn water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water .
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how come very strong acids ca n't dissolve as many substances than water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing .
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my question is , how did water come to form on earth ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying .
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i mean the north pole has ice and it probably melted , i get that , but how did the north pole get all the ice ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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where exactly did water generate from ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar .
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what is the strongest acid that we have ever created that hank spoke of ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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scratch that . water is n't a good solvent . it 's an amazing solvent .
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why does a large boat float on water but a small stone does n't ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars .
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was water always on earth ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid .
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does that mean the ionic bonds between the sodium chloride is broken by the polar attraction to the water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water .
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since the ocean and sea temp set the stage for weather in many instances why ca n't we control the water temp when a storm gets closer to shores to dissipate the storm ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars .
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why does water always make people think that water is blue but it is actually clear ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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why are water sometimes greenish blue in oceans , seas , and lagoons ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw .
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what is cohesion and adhesion ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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why does water expand when cooled ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible .
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why when other things are solid they are more dense ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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why does water evaporate when the sun shines down on it ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ?
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why is water necessary for life ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place .
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why does ice crack when it goes to a fast temperature change ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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scratch that . water is n't a good solvent . it 's an amazing solvent .
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are there any living organisms on earth that do n't need water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course .
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which lizard can walk on water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again .
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felicia ( ntcc ) why does water dissolve almost everything ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course .
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how do several bugs and a lizard manipulate the surface of water to be able to walk across it without sinking ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again .
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( ) why do hydrogen bonds cause the solid ice to be less dense than the liquid water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form .
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do all compounds that have hydrogen bonds have their solids be less dense then their liquid counterparts ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area .
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3. how did plants form ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it .
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why is it that the two hydrogen atoms bond with oxygen in a 'v ' shape , rather than bonding on opposite sides and forming a straight line ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule .
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when the first atom bonds , would n't it have a slightly +ve charge on the hydrogen side , forcing the second hydrogen atom to the opposite side of the oxygen atom , rather than one of the adjacent sides ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely .
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can someone explain water 's high latent heat of evaporation ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying .
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what would happen if ice never melts ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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scratch that . water is n't a good solvent . it 's an amazing solvent .
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when i take water in a jug from a bucket full of water wo n't this h-bond be disturbed ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example .
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what are some hydrophobic substances ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again .
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what is the exact definition of being wet ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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- > a tissue being wet by water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion .
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what is a capillary action ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar .
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what 's the greatest acid on earth ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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so how much of earth 's water might have been brought in by astroids ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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scratch that . water is n't a good solvent . it 's an amazing solvent .
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could n't earth have made its own bodies of water through its chemical interactions ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form .
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do the hydrogen bonds work only at molecular levels or do they also affect larger scales of water as well ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way .
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how did oxygen form on the earth ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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will our descendants not have water to drink ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles .
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why do people sound so sure about something that they have no proof on ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding !
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how did hydrogen atoms and oxygen atoms come to be ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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where did the first water come from ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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is hot water heavier than cold water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid .
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is it like how earth got its water ; from the comets source of water impacting it ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid .
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what would life be like without water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water .
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so , why does the scientific community get so excited about the possibility of finding water on mars ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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scratch that . water is n't a good solvent . it 's an amazing solvent .
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does n't a type of spider/insect walk on water too ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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can water be in a plasma state ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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is a hydrophobic substance pushed out of water by the cohesive forces because it 's non polar ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you .
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what is the latent heat of vaporization and is it another property of water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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how fast does a water bubble rise to the surface ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form .
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do hydrogen bonds occur anywhere else ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars .
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does water really turn into a gas ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way .
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what is a covalent bond , and what is its significance to h*2o ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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scratch that . water is n't a good solvent . it 's an amazing solvent .
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if water is the universal solvent , how many substances can it dissolve ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place .
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does n't ice cubes have air too ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion .
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i get that adhesion will cause water molecules to cling to the walls of a tube , and that cohesion will cause more water molecules to enter the tube , so wo n't cohesion itself be the cause of water moving upwards ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way .
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what would happen if there was two oxygen and one hydrogen ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying .
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would the water be gas ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion .
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so every time you have a glass of water that is just water molecules bonded to each other ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw .
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could we measure the power of the force of adhesion/cohesion in newtons ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it .
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why is the bonding between o and h called hydrogen bonding , although even oxygen is involved ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it .
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and 5 , even when the bond between o and h breaks , and they bond to other substances , why is it still called hydrogen bond ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion .
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so if water gets denser as it gets colder and cold water sinks , does the denser state affect how hard it is for a fish living deep in the ocean to swim through the water since the molecules are closer together ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life .
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what destroyed mars atmosphere , and also what happened to all the water on mars ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then .
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hank says surface tension will continue to cause water to climb up the straw until gravity overpowers it ; if this was done in a place without gravity ( or much of it ) , would the water climb until it fills the entire straw ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting .
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how would the gypsum deposit form in the way the rover found it ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you .
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regarding heat capacity -- is it possible that the atmosphere could be medium-strongly affected by global warming ( along with the stuff on surface ) but that the oceans will resist and maintain a certain degree of equilibrium ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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why does hot water seems to freeze faster than cold water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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scratch that . water is n't a good solvent . it 's an amazing solvent .
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should n't the cold water freeze faster than the hot water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar .
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what is the strongest acid we 've created ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid .
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what does the crystalline structure of ice look like ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge .
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i know water is v-shaped , but what does it look like in 3-d ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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but most of the covalent compound which are non-polar are not soluble in water but in stuff like ccl4 and other non polar solvents , and as there are like a million more covalent compounds than ionic ones , why is water still called the universal solvent , as there are solvents which dissolve more compounds than water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms .
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at the very beginning of the video hank says `` crash course hq '' what does hq mean ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again .
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why is water that dense ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion .
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i am curious i was taught that as substance 's temperatures decreased their molecules contracted , why does water expand ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds .
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is it possible to form a liquid in which the molecules are like water , but with slight modifications such as slightly more negative charge on the oxygen atom or less charge ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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why was the water it was showing dark blue ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw .
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is adhesion and cohesion the same as hydrophilic and hydrophobic ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything .
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why is the water blue instead of clear ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again .
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are most hydrophobic bonds , less dense than water ?
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man in glasses : hello , there . here at crash course hq we like to start out each day with a nice healthy dose of water in all its 3 forms . it 's the only substance on all of our planet earth that occurs naturally in solid , liquid and gas forms . to celebrate this magical bond between two hydrogen atoms and one oxygen atom , here today we are going to be celebrating the wonderful life-sustaining properties of water , but we 're going to do it slightly more clothed . ( boppy music ) ah , much better . when we left off here at the biology crash course we were talking about life , and the rather important fact that all life as we know it is dependent upon there being water around . scientists and astronomers are always looking out into the universe trying to figure out whether there is life elsewhere because that is kind of the most important question that we have right now . they 're always getting really excited when they find water someplace , particularly liquid water . this is one reason why i and so many other people geeked out so hard last december when mars ' seven-year-old rover opportunity found a 20-inch long vein of gypsum that was almost certainly deposited by long term liquid water on the surface of mars . this was probably billions of years ago , and so it 's going to be hard to tell whether or not the water that was there resulted in some life . maybe we can figure that out and that would be really exciting . why ? why do we think that water is necessary for life ? why does water on other planets get us so freaking excited ? let 's start out by investigating some of the amazing properties of water . in order to do that , we 're going to have to start out with this . the world 's most popular molecule , or at least the world 's most memorized molecule . we all know about it . good old h20 . two hydrogens , one oxygen , the hydrogens each sharing an electron with oxygen in what we call a covalent bond . as you can see , i 've drawn my water molecule in a particular way . this is actually the way that it appears . it is v-shaped . because this big old oxygen atom is a little bit more greedy for electrons , it has a slight negative charge ; whereas , this area here with the hydrogen atoms has a slight positive charge . thanks to this polarity , all water molecules are attracted to one another ; so much so that they actually stick together and these are called hydrogen bonds . we talked about them last time , but essentially what happens is that the positive pole around those hydrogen atoms bonds to the negative pole around the oxygen atoms of a different water molecule . it 's a weak bond , but look , they 're bonding ! seriously , i can not overstate the importance of this hydrogen bond . when your teacher asks you , `` what 's important about water ? '' start out with the hydrogen bonds and you should put it in all caps and maybe some sparkles around it . one of the cool properties that results from these hydrogen bonds is a high cohesion for water which results in high surface tension . cohesion is the attraction between two like things , like attraction between one molecule of water and another molecule of water . water has the highest cohesion of any nonmetalic liquid . you can see this if you put some water on some wax paper or some teflon or something where the water beads up like this . some leaves of plants do it really well ; it 's quite cool . since water adheres weakly to the wax paper or to the plant , but strongly to itself , the water molecules are holding those droplets together in a configuration that creates the least amount of surface area . this is high surface tension that allows some bugs and even i think one lizard and also one jesus to be able to walk on water . the cohesive force of water does have its limits , of course . there are other substances that water quite likes to stick to . take glass , for example . this is called adhesion . the water is spreading out here instead of beading up because the adhesive forces between the water and the glass are stronger than the cohesive forces of the individual water molecules in the bead of water . adhesion is attraction between two different substances , so in this case the water molecules and the glass molecules . these properties lead to one of my favorite things about water ; the fact that it can defy gravity . that really cool thing that just happened is called capillary action . explaining it can be easily done with what we now know about cohesion and adhesion . thanks to adhesion , the water molecules are attracted to the molecules in the straw . as the water molecules adhere to the straw , other molecules are drawn in by cohesion following those fellow water molecules . thank you cohesion . the surface tension created here causes the water to climb up the straw . it will continue to climb until eventually gravity pulling down on the weight of the water in the straw overpowers the surface tension . the fact that water 's a polar molecule also makes it really good at dissolving things , which we call it 's a good solvent then . scratch that . water is n't a good solvent . it 's an amazing solvent . there are more substances that can be dissolved in water than in any other liquid on earth . yes , that includes the strongest acid that we have ever created . these substances that dissolve in water , sugar or salt being ones that we 're familiar with , are called hydrophilic , and they are hydrophilic because they are polar . their polarity is stronger than the cohesive forces of the water . when you get one of these polar substances in water , it 's strong enough that it breaks all the little cohesive forces , all those little hydrogen bonds . instead of hydrogen bonding to each other , the water will hydrogen bond around these polar substances . table salt is ionic , and right now it 's being separated into ions as the poles of our water molecules interact with it . what happens when there is a molecule that can not break the cohesive forces of water ? it ca n't penetrate and come into it . basically , what happens when that substance ca n't overcome the strong cohesive forces of water , ca n't get inside of the water ? that 's when we get what we call a hydrophobic substance , or something that is fearful of water . these molecules lack charged poles . they are non-polar and are not dissolving in water because essentially they 're being pushed out of the water by water 's cohesive forces . water , we may call it the universal solvent , but that does not mean that it dissolves everything . ( boppy music ) there have been a lot of eccentric scientists throughout history , but all this talk about water got me thinking about perhaps the most eccentric of the eccentrics , a man named henry cavendish . he communicated with his female servants only via notes , and added a staircase to the back of his house to avoid contact with his housekeeper . some believe he may have suffered from a form of autism , but just about everyone will admit that he was a scientific genius . he 's best remembered as the first person to recognize hydrogen gas as a distinct substance and to determine the composition of water . in the 1700s , most people thought that water itself was an element , but cavendish observed that hydrogen , which he called inflammable air , reacted with oxygen , known then by the awesome name , dephlogisticated air , to form water . cavendish did n't totally understand what he 'd discovered here , in part because he did n't believe in chemical compounds . he explained his experiments with hydrogen in terms of a fire-like element called phlagiston . nevertheless , his experiments were groundbreaking . like his work in determining the specific gravity basically the comparative density of hydrogen and other gases with reference to common air . it 's especially impressive when you consider the crude instruments he was working with . this , for example , is what he made his hydrogen gas with . he went on not only to establish an accurate composition of the atmosphere , but also discovered the density of the earth . not bad for a guy who was so painfully shy that the only existing portrait of him was sketched without his knowledge . for all of his decades of experiments , cavendish only published about 20 papers . in the years after his death , researchers figured out that cavendish had actually pre-discovered richter 's law , ohm 's law , coulomb 's law , several other laws . that 's a lot of freaking laws . if he had gotten credit for them all , we would have had to deal with like cavendish 's 8th law and cavendish 's 4th law , so i , for one , am glad that he did n't actually get credit . we 're going to do some pretty amazing science right now . you guys are not going to believe this . okay , you ready ? it floats ! yeah , i know you 're not surprised by this , but you should be because everything else , when it 's solid is much more dense than when it 's liquid ; just like gases are much less dense than liquids are . but that simple characteristic of water that its solid form floats is one of the reasons why life on this planet , as we know it , is possible . why is it that solid water is less dense than liquid water while everything else is the exact opposite of that ? well , you can thank your hydrogen bonds once again . at around 32 degrees fahrenheit or 0 degrees celsius if you 're a scientist or from a part of the world where things make sense , water molecules start to solidify and the hydrogen bonds in those water molecules form crystalline structures that space molecules apart more evenly , in turn making frozen water less dense than its liquid form . so in almost every circumstance a floating water ice is a really good thing . if ice were denser than water it would freeze and then sink , and then freeze and then sink , and then freeze and then sink , so just trust me on this one . you do n't want to live on a world where ice sinks . not only would it totally wreak havoc on aquatic eco systems which are basically how life formed on the earth in the first place . also , all the ice in the north pole would sink and then all of the water everywhere else would rise and we would n't have any land . that would be annoying . there 's one more amazing property of water i 'm forgetting . why is it so hot in here ? heat capacity ! yes , water has a very high heat capacity and probably that means nothing to you . basically it means that water is really good at holding on to heat , which is why we like to put hot water bottles in our bed and cuddle with them when we 're lonely . aside from artificially warming your bed , it 's also very important that it 's hard to heat up and cool down the oceans significantly . they become giant heat sinks that regulate the temperature and the climate of our planet , which is why , for example , it 's so much nicer in los angeles where the ocean is constantly keeping the temperatures the same than it is in , say , nebraska . on a smaller scale , we can see water 's high heat capacity really easily and visually by putting a pot with no water in it on a stove and seeing how badly that goes . but then you put a little bit of water in it and it takes forever to freaking boil ! and if you have n't already noticed this , when water evaporates from your skin , it cools you down . that 's the principle behind sweating , which is an extremely effective , though somewhat embarrassing , part of life . this is an example of another incredibly cool thing about water . when my body gets hot and it sweats , that heat excites some of the water molecules on my skin to the point where they break those hydrogen bonds and they evaporate away . when they escape , they take that heat energy with them , leaving me cooler . lovely . this was n't exercise , though . i do n't know why i 'm sweating so much . it could be the spray bottle that i keep spraying myself with , or maybe it 's just because this is such a high stress enterprise trying to teach you people things .
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scratch that . water is n't a good solvent . it 's an amazing solvent .
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how come water is so crucial to sustain life are n't there other liquids that fit the bill ?
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