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What's up with SiO2 being tetrahedral? |
My question is: Is hydrogen-rich water true? I am aware of the alkaline water. I have read several articles in the Internet regarding this kind of water but I cannot seem to be convinced. Wikipedia isn't even talking about it.
I am puzzled with how can a water be enriched with hydrogen. It's definitely H2O and every... |
Question is rather self-explanatory. Came up during a lecture without a concrete answer.
I understand that the differences in emission wavelengths is due to relaxation to the lowest energy level of S1, but **why do fluorescent molecules necessarily overlap in their excitation and emission spectra?** |
Why does the excitation and emission spectrum of a fluorescent molecule have overlap? |
If silicon dioxide tends to form a crystal lattice with four Os around a central S, why isn't the molecular formula $\ce{SiO4}$ then? I'm confused why it's unique in that its molecular formula doesn't match up with its geometry.
I know it can be hard but please explain in a way a lowly gen chem 1 student like myself... |
Recently, our water from the artesian well started to smell (again). It only smells bad for only few seconds than the smell disappear. We have sulfur-iron removal system, water softener, UV lamp. Only the water from the system I listed above smell, because we also have a Reverse Osmosis installed in the kitchen and th... |
What can cause artesian well water to smell? |
I have been reading up on this website
http://www.brighthubengineering.com/thermodynamics/4616-what-are-reversible-and-irreversible-processes/
about the difference between reversible and irreversible thermodynamic process and it defines them saying that reversible processes are ideal processes while irreversible ... |
I have been reading up on [this website][1] about the difference between reversible and irreversible thermodynamic process and it defines them saying that reversible processes are ideal processes while irreversible processes are the natural processes. Are these definitions correct?
If not, how are the two defined... |
I have been reading up on this website about the difference between reversible and irreversible thermodynamic process and it defines them saying that reversible processes are ideal processes while irreversible processes are the natural processes. Are these definitions correct?
If not how are they defined? |
I have been reading up (on [this website][1]) about the difference between reversible and irreversible thermodynamic process and it defines them saying that reversible processes are ideal processes while irreversible processes are the natural processes. Are these definitions correct?
If not how are they defined?
... |
I'm trying to do compound optimization for acetic acid on a EI-MS.
Later on it would be also run via HPLC to the MS.
But I do only get fragments of 53/54 and 32.
Also I need a high concentration to be able to do a compound optimization for the 32 fragment (...around 1mM solution).
I looked up other mass spectra ... |
I have the following question.
The potential energy of two atoms, a distance "r" apart, is U = -A/r^m + B/r^n , where m=2 and n=10. Given that the atoms form a stable molecule at a separation of 0.3nm with an energy of -4eV, calculate A and B. Also find the force required to break the molecule, and the critical sepa... |
I have the following question.
The potential energy of two atoms, a distance $r$ apart, is: $$U = -Ar^{-2} + Br^{-10}$$ Given that the atoms form a stable molecule at a separation of 0.3nm with an energy of -4 eV, calculate $A$ and $B$. Also find the force required to break the molecule, and the critical separation ... |
What about an ammonia-based fluid mix? I saw one guy on youtube that said he made it with Windex (the liquid was a clear greenish color) and another guy said he made it with Windolene(he's in the UK) but it went cloudy after a while. Meanwhile doing some other research I found someone who says their product (they sell... |
I have the following question.
The potential energy of two atoms, a distance $r$ apart, is: $$U = -Ar^{-2} + Br^{-10}$$ Given that the atoms form a stable molecule at a separation of 0.3nm with an energy of -4 eV, calculate $A$ and $B$. Also find the force required to break the molecule, and the critical separation ... |
According to our book, when the solution is dilute, the mole fraction of solute can be given as:
X2 = molality (m) x mass of solvent (M1) / 1000
(Actually it is written as:
X2 = m / 1000/M1)
How is this true?
The only reason i can think of is that as the solution is dilute, X2 should almost be equal to z... |
According to our book, when the solution is dilute, the mole fraction of solute can be given as:
X2 = molality (m) x mass of solvent (M1) / 1000
Actually it is written as:
X2 = m/(1000/M1)
How is this true?
The only reason i can think of is that as the solution is dilute, X2 should almost be equal to zer... |
If one consider boiling points ($^{o}C$) of primary alcohols, one finds the following:
- methanol: 65
- ethanol: 79
- 1-propanol: 97
- 1-butanol: 117
- 1-pentanol: 138
This trend is due to Wan der Waals forces increasing with molecular weight.
Now if one focus on melting points, I would expect the... |
Melting points are a bit trickier to compare than boiling points, especially when you're looking at the lightest examples of a group of molecules. [This graph][1] for the unbranched alkanes exemplifies nicely how the trends differ in smoothness.
As you increase the weight of molecules, the observed trend depends on... |
Melting points are a bit trickier to compare than boiling points, especially when you're looking at the lightest examples of a group of molecules. [This graph][1] for the unbranched alkanes exemplifies nicely how the trends differ in smoothness.
As you increase the weight of molecules, the observed trend depends on... |
Melting points are a bit trickier to compare than boiling points, especially when you're looking at the lightest examples of a group of molecules. [This graph][1] for the unbranched alkanes exemplifies nicely how the trends differ in smoothness.
As you increase the weight of molecules, the observed trend depends on... |
For the exothermic reaction of nitrogen gas with iodine solid to produce nitrogen triodide gas.?
Write the balanced equation including heat and select the overall direction of shift in the reaction.
Here is the balanced equation:
N2 (g) + 3 I2 (g) = 2 NI3 |
For the exothermic reaction of nitrogen gas with iodine solid to produce nitrogen triodide gas.?
Write the balanced equation including heat and select the overall direction of shift in the reaction.
|
For the exothermic reaction of nitrogen gas with iodine solid to produce nitrogen triodide gas.?
Write the balanced equation including heat and select the overall direction of shift in the reaction.
I have balanced the equation: N2 (g) + 3 I2 (g) = 2 NI3
I am confused on how to find the overall direction of shif... |
For the exothermic reaction of nitrogen gas with iodine solid to produce nitrogen triodide gas.?
Write the balanced equation including heat and select the overall direction of shift in the reaction.
I have balanced the equation: $\ce{N2 (g) + 3 I2 (g) <=> 2 NI3}$
I am confused on how to find the overall directio... |
For the exothermic reaction of nitrogen gas with iodine solid to produce nitrogen triodide gas.?
Write the balanced equation including heat and select the overall direction of shift in the reaction.
I have balanced the equation: $\ce{N2 (g) + 3 I2 (g) <=> 2 NI3}$
Is this equation correct?
I am confused on how t... |
My intuition says no, but I am having trouble coming up with concrete examples.
I know that minimizing Gibbs free energy predicts a state of equilibrium, while minimizing kinetic or internal energy does not correspond to equilibrium. However, I am not so sure about potential energy--- when PE is at a minimum, is the... |
Does minimizing ANY type of energy ALWAYS predict a state of equilibrium? |
What is pre-concentration (context: Breath analysis)? |
Following which path can an hydrogen atom be exchanged with a deuterium atom ? This is by curiosity. |
I would like to ask how many valence electrons took part in creating chemical bond in OH-? Is the minus related to O or to H? Are there any spare valence electrons which didnt take part in creating chemical bond in OH-? |
Melting points are a bit trickier to compare than boiling points, especially when you're looking at the lightest examples of a group of molecules. [This graph][1] for the unbranched alkanes exemplifies nicely how the trends differ in smoothness.
As you increase the weight of molecules, the observed trend depends on... |
I would like to ask about formula of phosphorus oxide (V). Should it be P4010 or P205? which is right when I have to write molecular formula |
Phosphorus Oxide (V) - a proper formula - is it $\ce{P4}$$\ce{O10}$ or $\ce{P2}$$\ce{O5}$? |
I would like to ask about formula of phosphorus oxide (V). Should it be $\ce{P4}$$\ce{O10}$ or $\ce{P2}$$\ce{O5}$? which is right when I have to write molecular formula |
What's the mechanism for this isotopic substitution reaction? |
This may be a very broad question.
I always asked myself how scientists manage to find out the exact molecular structures of for instance water or carbohydrates. How do they know? How do they know the angle between the bonds in water? Is there a classical example demonstrating and substantiating current knowledge on m... |
There are many types of plastics that can be used for food packaging, for example:
- Polyethylene terephthalate (PET)
- Polyethylene (PE)
- Polyvinyl chloride (PVC)
- Polypropylene (PP)
What are the differences between them?
Which one is most suitable for packaging pastries, for example, biscuits?
|
Take acetylene, for example.
![enter image description here][1]
[1]: https://i.stack.imgur.com/NI1Qe.png
It is defined that the two outer bonds are at 180 degrees. How can this be made certain? |
How can it be certain that some bonds are 180 degrees? |
Take acetylene, for example.
![enter image description here][1]
[1]: https://i.stack.imgur.com/NI1Qe.png
It is defined that the two outer bonds are at 180 degrees.
How is it possible to theoretically define all C-H bonds in acetylene as being 180 degrees? |
In a similar vein and for pretty much the same reason as I post [this question on the Physics.SE site][1], what would be a an effective means to promote understanding about redox reactions to a 6 year old? In particular, what (if any) simulations are available?
[1]: http://physics.stackexchange.com/questions/76... |
Explaining redox reactions to a 6 year old? |
[Energy-Level Diagram][1]
<br>There is overlap because between the excitation and the emission spectra because there exists a Range of orbitals at different energies. You'll always notice that the energy for excitation is always higher, or the lambda value is always lower (these say the same thing since E=planck's con... |
I admit that my knowledge of collision theory may be lacking, but, as I understand it, when particles collide, a reaction will not occur without overcoming the activation energy.
That being said, as the temperature of the environment in which the collision takes place is decreased, I believe it is logical that the ... |
When temperature is decreased, why do reactions occur at all? |
I ran this question past our mass spec. guy, and he offers the following suggestions:
- Have you run a blank to ensure you are not just measuring some other random compound; Or contaminants from the instrument; Or gas system.
- Be aware when measuring ions less than 45m/z that you are not just measuring ions from... |
How is the spontaneity of an exothermic reaction changed when temperature is decreased?
Assuming the entropy is negative.
Using Gibbs free energy equation, G=H-TS, G should become less negative as temperature is decreased meaning the reaction is less spontaneous. However, using Le Chatelier's principle, as tempera... |
Silver compounds such as silver fluoride are light sensitive (as are all other silver halides) so they will decompose when exposed to light.
I'm stuck with a problem : I want to expose silver(I)fluoride to light to then produce elemental silver and fluorine gas - I'm worried that because of the high reactivity of fl... |
If we replace two oxygen in $-COOH$ what is the name of the compound we get? |
Which functional group is $-CSSH$? |
Difference between sodium ion and a transition metal ion dissolving in water? |
#Charge density#
Charge density is the density of charge around the ion. Silberberg (Chemistry: The Molecular Nature of Matter and Change. 4th ed. 2006) define it as:
> "The ratio of the charge of an ion to its volume."
The factors playing into the strength of an ion's charge density are therefore the *charge o... |
For example (for reductions)
$$
\ce{2e-} + \ce{Cd^{2+}} \rightarrow \ce{Cd}:\mbox{ } E^0 = -0.403 V\\
\ce{2e-} + \ce{Ni^{2+}} \rightarrow \ce{Ni}:\mbox{ } E^0 = -0.25 V
$$
How can I rationalize this difference?
|
How can normal potentials be explained? |
How is the spontaneity of an exothermic reaction changed when temperature is decreased?
Assuming the entropy is negative.
Using Gibbs free energy equation, $\Delta G=\Delta H-T\Delta S$, $\Delta G$ should become less negative as temperature is decreased meaning the reaction is less spontaneous. However, using Le C... |
I'm trying to do compound optimization for acetic acid on a EI-MS.
Later on it would be also run via HPLC to the MS.
But I do only get fragments of 53/54 and 32.
Also I need a high concentration to be able to do a compound optimization for the 32 fragment (...around 1mM solution).
I looked up other mass spectra ... |
What's the difference between $\alpha$-D-glucose and $\beta$-D-glucose? Are they isoforms? Or do they differ in their elemental composition? |
What's the difference between alpha-glucose and beta-glucose? |
My book says that benzoic acid does not show resonance as the carboxylate ion and the benzene ring are not in the same plane due to steric effects.
But there aren't any large group in the ortho positions to show steric inhibition of resonance.![Benzoic Acid][1]
[1]: https://i.stack.imgur.com/5HmlZ.jpg
Th... |
I would like to understand the temperature at which a substance will vaporize when dissolved in a liquid. I have researched this online for hours, but haven't found a conclusive answer. Is it the boiling point of the dissolved substance? I'm attempting to find the temperature at which caffeine vaporizes when dissolved ... |
How do I determine the temperature at which a dissolved substance evaporates? |
I produce high density balsamic vinegar,
when it's winter and the temperatures are very low, High density products tends to crystallize . *I think this is a problem of over saturation of the glucose / aw .*
The main sugars are glucose and fructose the ratio is 1:0.95 .
I try make products that are lower than 70 b... |
Crystallization of sugars problem? |
Would you add in NaOH, deprotonating the acid, and then wash the mixture in water, thereby removing the Na+ and CH3O- ions in an aqueous layer? But then wouldn't the ethanol be dissolved in the water as well, as it is polar? In general, how do you separate two polar substances from each other using extraction?
If yo... |
How does one separate ethanol from acidic acid using aqueous extraction? |
I know outer electrons include (n-1)d...+ all n'ss.. But i don't understand, never been told what unpaired electron is supposed to be? is it the same thing.
so in the following electron configuration:
4s2 3d10 4p3:
OuterElectrons: 15
ValenceElectrons: 5
from what i remember someone told be unpaired elect... |
This is a [Google ngram](https://books.google.com/ngrams/graph?content=(Zinc+-+_START_+Zinc)%2Czinc%2C(Iodine+-+_START_+Iodine)%2Ciodine%2Cnitrogen%2C(Nitrogen+-+_START_+Nitrogen)%2Ccarbon%2C(Carbon+-+_START_+Carbon)&year_start=1800&year_end=2000&corpus=15&smoothing=3&share=&direct_url=t1%3B%2C%28Zinc%20-%20%20_START_%... |
This is a [Google ngram](https://books.google.com/ngrams/graph?content=(Zinc+-+_START_+Zinc)%2Czinc%2C(Iodine+-+_START_+Iodine)%2Ciodine%2Cnitrogen%2C(Nitrogen+-+_START_+Nitrogen)%2Ccarbon%2C(Carbon+-+_START_+Carbon)&year_start=1800&year_end=2000&corpus=15&smoothing=3&share=&direct_url=t1%3B%2C%28Zinc%20-%20%20_START_%... |
In [this video](https://www.youtube.com/watch?v=yBrp8uvNAhI), Sal Khan says that an electron reaches a higher energy state if the electron possesses more energy. So I assume that, say in the case of carbon, the electrons not in the S1 orbital have more energy. Where does this energy come from? |
Where do the electrons not in the S1 orbital get this "extra energy" from? |
How does one separate ethanol from acetic acid using aqueous extraction? |
When do covalent bonds of a molecule $M$ extend or compress while no bonds in $M$ are broken? I can conceive of some possibilities but I don't know how common they are:
- Temperature changes
- Inter-molecular forces around $M$ which may stretch or compress $M$ in various directions
- The transition from $M$ int... |
![enter image description here][1]
[1]: https://i.stack.imgur.com/bnWO5.jpg
I'm confused about how this chair conformation was constructed and why that particular Cl leaves. Why is one of the Cl's drawn axial while the others are drawn equatorial (it seems like the others could have been drawn axial as well)?... |
Why is this chair conformation the most stable and which leaving group is best? |
I know outer electrons include (n-1)d...+ all n'ss.. But i don't understand, never been told what unpaired electron is supposed to be? is it the same thing.
so in the following electron configuration:
$4s^2\: 3d^{10}\: 4p^3$:
OuterElectrons: $15$
ValenceElectrons: $5$
from what I remember someone told me... |
First, it is a good idea to clarify the meaning of the word **vaporize** from [here](http://www.thefreedictionary.com/vaporize):
> 1. (Physics / General Physics) to change or cause to change into vapour or into the gaseous state
> 2. to evaporate or disappear or cause to evaporate or disappear, esp suddenly
> 3. (... |
I really want to make liquid nitrogen(or oxygen) without using dry is, a specially made freezer or other chemicals.
I have a mixture of some sponges, rotten grass, sugar and water, which makes pressure in the bottle(produces co2). which temperatures can i expect if i freeze it and then quickly opens the bottle after... |
is it possible to make liquid nitrogen with a bottle of co2 gas and a freezer? |
I really want to make liquid nitrogen(or oxygen) without using dry ice, a specially made freezer, or other chemicals.
I have a mixture of some sponges, rotten grass, sugar and water, which makes pressure in the bottle(produces $\ce{CO2}$). Which temperatures can I expect if I freeze it and then quickly opens the bot... |
Is it possible to make liquid nitrogen with a bottle of CO2 gas and a freezer? |
If you have an aromatic ring that requires substitution of some molecule, how do you know where this molecule is supposed to substitute on the ring?
![enter image description here][1]
[1]: https://i.stack.imgur.com/ihAw6.jpg
In (i) and (ii) how do we select the ring that will receive the molecule (HSO3 in ... |
Where do things connect in EAS reactions? |
If you have an aromatic ring that requires substitution of some molecule, how do you know where this molecule is supposed to substitute on the ring?
![enter image description here][1]
[1]: https://i.stack.imgur.com/ihAw6.jpg
In (i) and (ii) how do we select the ring and position that will receive the molec... |
I understand the principal of the Cis-Trans naming system (at least I think so), until I saw this example in my learning material. My teacher doesn't know either so I thought I would post it here.
This is the molecule:
![enter image description here][1]
There are two ethyl groups both on the bottom side of the d... |
Nomenclature for stereoisomer example possible wrong? |
![enter image description here][1]
[1]: https://i.stack.imgur.com/VRzSN.jpg
I'm confused, because it seems like Huckel's rule is satisfied and that the molecule should be aromatic. Where am I going wrong here? |
Why isn't this molecule aromatic? |
In science, the acid-base equilibrium constant potential is denoted ![pK_a][1] or ![pK_A][2] depending of the source (lowercase or uppercase A). Since it is the potential of the acide-base equilibrium constant defined as
![K_A aquation][3]
I would write ![pK_A][4] (the LaTeX package `chemmacros` write it so but d... |
What is the correct form for the acid-base equilibrium constant potential: pK_a or pK_A? |
I have pretty much zero experience in chemistry whatsoever but I wonder about how much crystal will I get from fully dissolved element when I reduce water temperature.
**Variables**
- at 40°C 171g of Pb(NO3)2 is fully dissolved in water
- at 18°C Pb(NO3)2 - How much is dissolved now? Everything that was not di... |
First, it is a good idea to clarify the meaning of the word **vaporize** from [here](http://www.thefreedictionary.com/vaporize):
> 1. (Physics / General Physics) to change or cause to change into vapour or into the gaseous state
> 2. to evaporate or disappear or cause to evaporate or disappear, esp suddenly
> 3. (... |
I learned that the order of +M effect (mesomeric effect) for halogens are as follow : `F > Cl > Br > I`
I wonder why it is so? |
Let's speak the Redox with an exempla : Corrosion off a piece of Iron.And Oxygene around you and me. As child of 6 years old had probably seen this, it will directly rely to everyday 's live.
Say this to him : You cannot see the "messy movements" in this Iron because your eyes are too big.......and because you can s... |
How can I theoretically predict the time needed to photolyze n moles of AgF? (with UV) (this is not a homework question)
The photolysis of AgF requires UV light - but I don't know which wavelength the UV must be at for the optimal photolysis. Then if the wavelength is known I can calculate the energy of one UV photo... |
I learned that the order of +M effect (mesomeric effect) for halogens is as follow : `F > Cl > Br > I`
I wonder why it is so? |
Why the dihydroxyacetone phosphate is called that way when it has only one OH ? |
Because it is the phosphoester of dihydroxyacetone. One of the -OH groups was used in the esterification reaction.
See here:
http://guweb2.gonzaga.edu/faculty/cronk/biochem/D-index.cfm?definition=DHAP |
Why is CuSO4 used as electrolyte while purifying copper? |
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