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I'm reading a review article on photocatalytic water splitting (using semiconductors) and I came across the following:
"To achieve photocatalytic water splitting using a single photocatalyst, the bandgap of the semiconductor must straddle the reduction and oxidation potentials of water, which are +0 and +1.23 V vs t... |
I wrote this long answer to a question which was deemed "duplicate" but really asked a more specific question, why there are the gaps in the periodic table etc.
The elements are organized in groups (the columns) because the elements in each group have very similar chemical properties.
For example, the noble gases... |
I would like to understand how a mixture of solvents works together.
For example, there are two solvents combined, and each one allone can dissolve some material, but one acts faster.
How do they interact when used in combination on the same material?
<br>
An example would be paint thinner, for example a ... |
Mixing solvents, or how does paint thinner work? |
As part of a synthesis I was considering the following reaction:
![enter image description here][1]
Is this a viable reaction? I know that the Clemmensen reduction favours ketones adjacent to benzene rings but will it also reduce the other ketone, and/or affect any other parts of the molecule. Are there any other... |
I've just found read that entropy increases through these reasons:
1. Changing the phase of the elements to a gas.
2. Increasing the **molar mass of that specific element** increases the entropy.
I understand the first one, but I cant grasp the second one.
Because naturally you would think that $\ce{H2}$ wo... |
Why are the axial bond lengths greater than those of the equatorial bonds in a pentagonal bi-pyramid (PBP) geometry molecule; but the opposite is true for trigonal bi-pyramid (TBP) geometry molecules? I think that it might have something to do with the angles between the bonds, so I thought of a possible explanation.
... |
As part of a synthesis I was considering the following reaction:
![enter image description here][1]
How selective is the Clemmensen reduction? I know that the Clemmensen reduction favours ketones adjacent to benzene rings but will it also reduce the other ketone, and/or affect any other parts of the molecule. Are... |
![enter image description here][1]
The correct answer (that is false) is A) however can someone please explain why the other options would be true and why it is in fact possible to compress a solid to produce a liquid?
[1]: https://i.stack.imgur.com/4uC8U.png |
Interpreting a Phase Diagram? |
You don't really need to do anything to get LPG vapour. It is a gas a room temperature and pressure so as long as you just want the clean gas not mixed with air (which would be dangerous as the mixture will be flammable and potentially explosive), all you need to do is allow the output of the canister to vent into a ba... |
I had the following question on my nuclear chemistry test today:
What product is formed when Curium-226 undergoes alpha decay?
Curium has atomic number 96. Since alpha decay decreases the number of protons and neutrons by 2, the product formed has atomic number 94 and atomic mass 222, thus the product is Plutoni... |
What is the product of alpha decay of Curium-226? |
I was recently doing some organic chemistry work and came across a set of problems.
"Which of the following compounds will participate in hydrogen bonding with water? For each compound, indicate whether it will be a hydrogen bond donor, hydrogen bond acceptor, or both."
I do not have an idea of how to approach th... |
I was recently doing some organic chemistry work and came across a set of problems.
"Which of the following compounds will participate in hydrogen bonding with water? For each compound, indicate whether it will be a hydrogen bond donor, hydrogen bond acceptor, or both."
I do not have an idea of how to approach th... |
What are the alternatives to the Periodic Table of the Elements? |
I would like to understand how a mixture of solvents works together.
For example, there are two solvents combined, and each one allone can dissolve some material, but one acts faster.
How do they interact when used in combination on the same material?
<br>
An example would be paint thinner, for example a ... |
I learnt about intermolecular hydrogen bonding today, which occurs between molecules such as [ortho-nitrophenol][1]. What I was told is that in case of intermolecular bonding, the molecules separate from each other, opposite of what happens during intramolecular hydrogen bonding.
I don't understand why is this. Why ... |
According to Wikipedia: "A magnon is a quasiparticle, a collective excitation of the electrons' spin structure in a crystal lattice."
I have little pictures in my mind for other quasiparticles. For example, I can picture a phonon as (quantized) vibrations in a crystal lattice, or I can picture excitons as an electro... |
How to visualize or think about spin waves (magnons)? |
I am looking for a liquid that illuminates when vibrations are added.
It does not have to be strictly chemical, it might as well be something else as well.
Maybe a crystal in powder form mixed with some kind of oil, or even algae in a thick:ish liquid.
Does such a liquid exist? |
Does liquids that emit light when vibrated exist? |
I'm having quite a fair bit of trouble comprehending the hybridization of cyclohexane. I understand that this is a ringed structure with single C-C bonds, therefore all the carbons should have sp3 hybridization right?
Apparently however, this is incorrect, but I am not sure why. I'm reading about how it not planar ... |
Understanding the hybridization of cyclohexane? |
> I'm having quite a fair bit of trouble comprehending the hybridization
> of cyclohexane.
Atoms can be hybridized. Not entire molecules. Just atoms.
> I understand that this is a ringed structure with single C-C bonds,
> therefore all the carbons should have sp3 hybridization right?
Yes, all the carbons in... |
> I'm having quite a fair bit of trouble comprehending the hybridization
> of cyclohexane.
Atoms can be hybridized. Not entire molecules. Just atoms.
> I understand that this is a ringed structure with single C-C bonds,
> therefore all the carbons should have sp3 hybridization right?
Yes, all the carbons in... |
When I wet an aluminum pot or cookie sheet and then dry it with a towel, it creates dark gray marks on the towel. This happens more if the aluminum is a little rough. It seems that there's a fine black powder coming off the aluminum. I would guess that's aluminum oxide, but I was under the impression that aluminum oxid... |
Why does the black powder that comes off aluminum pans behave the way it does? |
I've just found read that entropy increases through these reasons:
1. Changing the phase of the elements to a gas.
2. Increasing the **molar mass of that specific element** increases the entropy.
I understand the first one, but I can't grasp the second one.
Because naturally you would think that $\ce{H2}$ w... |
I've just found read that entropy increases through these reasons:
1. Changing the phase of the elements to a gas.
2. Increasing the **molar mass of that specific element** increases the entropy.
I understand the first one, but I can't grasp the second one.
Because naturally you would think that $\ce{H2}$ w... |
Atkins book talks about the molar fraction term in Raoults law as if it were of the entire system.
Levine says that Raoults law has the form $P_i = x^l_i P_iº$ which looks as if she were saying that $x^l_i$ is the molar fraction in the liquid.
So what is it really? and why would Levine have that notation?
Lev... |
Raoults law. Is the molar fraction the molar fraction in the entire system? |
for the net ionic equation I got
NaOH(s)+H2O(l)==>Nah+(aq)+OH-(aq)+H2O(l)
but it was wrong.
Then I tried:
NaOH(aq) ==> Na+ (aq)+ OH- (aq)
and it was wrong as well..
can someone please explain?
|
Net ionic equation of sodium hydroxide when it dissolves in water? |
Phosgene ($\ce{O=CCl2}$) is a potent toxin and in no way would I consider it a safe or even standard laboratory reagent (at least on an undergraduate level).
Allow me to lead you down the garden path of organic synthesis.
We have a haloalkane. What do we know about such compounds; they have a polarised C-X bond (... |
![question][1]
[1]: https://i.stack.imgur.com/r0L5x.jpg
In this question immediate reaction is to make a grignard reagent with B by reacting it with magnesium and have it attack $\ce{COX(N(Me)2)}$ to form $\ce{C}$
Im not sure how it would be possible to make $\ce{COX(N(Me)2)}$ from standard reagents.
A... |
Solomons and Fryhle has an example in which they have showed a very simple substitution reaction. The question was to synthesize methyl iodide. What they have done is taken methyl chloride and produced methyl iodide in the presence of NaI and ethanol through an SN2 mechanism. My question is -why did they use ethanol? I... |
Where did you find the statement: "all substitution reactions on methyl go through $S_N1$"? It is obviously wrong. Methyl definitely favor $S_N2$.
Here is the answer. The conversion from $MeCl$ to $MeI$ go through $S_N2$ mechanism. The best solvent for $-Cl$ to $-I$ conversion is usually **acetone**. It is cheap, po... |
Firstly, I am sorry I have NO understanding of chemistry etc so these to chemical formulas mean nothing to me, what I am trying to ascertain is are they the same? If not what differences are there especially if injected into the CSF [which they were]
(1.)
Iodine linked to CH3
I (CH2)8 COOC2 H5
... |
I have no understanding of chemistry, so these to chemical formulas mean nothing to me. What I am trying to ascertain is are these compounds the same? If not, what differences are there especially if injected into the CSF [which they were]?
1. Known as Ethyl Iodophenylundecylate:
CH3
I (CH2)8... |
Are ethyl iodophenylundecylate and Ethyl-10-(Iodophenylundecanoate) the same compound? |
I have read numerous online questions similar to the one I am about to ask. But for most of them the answer has been that the reason one can add water to the unknown concentration solution during a titration is because:
1) Water has a pH of 7
2) This is a volumetric analysis, so as long as one record the volume o... |
I am interested to learn through heat claculations the quantity of ice that would achieve a chicken carcass core temperature of 8 degree C.
My chilling tank has a volume of 15,000 liters of flowing water where chicken pass through at a rate of 3,000 carcass per hour having an average carcass weight of 1.4kg and deep... |
I've always been taught that an exothermic dissolution means that the forming of solute-solvent bonds releases more energy than the energy consumed to break solute-solute bonds and solvent-solvent bonds. However, if the attraction that occurs between solute and solvent particles are mainly based off of intermolecular f... |
Why do Exdothermic Dissolution Reactions occur? |
I had the following question on my nuclear chemistry test today:
> What product is formed when Curium-226 undergoes alpha decay?
Curium has atomic number 96. Since alpha decay decreases the number of protons and neutrons by 2, the product formed has atomic number 94 and atomic mass 222, thus the product is Pluto... |
The "structures" you are trying to post and their respective names do not match, as I cannot spot a phenyl group in there. (Also it is hard to tell from this diagram.) But based on what you gave us, I believe these are the same compounds, where ethyl 10-(4-iodophenyl)undecanoate is the correct IUPAC name and Ethyl iodo... |
Why do exothermic dissolution reactions occur? |
for the net ionic equation I got
$$\ce{NaOH_{(s)} + H2O_{(l)} -> NaH+_{(aq)} + OH^{-}_{(aq)} + H2O_{(l)}}$$
but it was wrong.
Then I tried:
$$\ce{NaOH_{(aq)} ==> Na+_{(aq)} + OH^{-}_{(aq)}}$$
and it was wrong as well..
can someone please explain?
|
What is the net ionic equation of sodium hydroxide when it dissolves in water?
For the net ionic equation I got
$$\ce{NaOH~(s) + H2O~(l) -> NaH+~(aq) + OH^{-}~(aq) + H2O~(l)}$$
but it was wrong.
Then I tried:
$$\ce{NaOH~(aq) -> Na+~(aq) + OH^{-}~(aq)}$$
and it was wrong as well.
Can someone please explain... |
What is the net ionic equation of sodium hydroxide when it dissolves in water? |
> How much sulphuric acid $(H_2SO_4)$ can be obtained from 5 kg of sulphur($S_8$)?
*answer: 15.312kg*
okey this formula of sulphuric acid has 1 S that is in 1 molecule of $H_2SO_4$ contains 1 atom of S so to make 1 molecules of $H_2SO_4$ we need 1 atoms of S. <br>
now coming to $S_8$. This gives us 8 atoms of ... |
> How much sulphuric acid $(\ce{H2SO4})$ can be obtained from 5 kg of sulphur$(\ce{S8})$?
*answer: 15.312kg*
okey this formula of sulphuric acid has 1 S that is in 1 molecule of $\ce{H2SO4}$ contains 1 atom of S so to make 1 molecules of $\ce{H2SO4}$ we need 1 atoms of S. <br>
now coming to $S_8$. This gives u... |
The answer, in principal, is not. But, based on your info, the correct structure is not so easy to determine and the reason is, as Martin states, there is no info related the positions of the functional groups (This is to say the Iodine and the phenyl). However and taken literally the structure name you shared, the str... |
$\ce{S6}$, $\ce{S8}$, $\ce{S12}$ - does it make a difference or is it just a trick to make the question more complicated than it is?
What you know for sure is:
- M($\ce{S}$) = $32.065\ \mathrm{g}\cdot \mathrm{mol}^{-1}$
- M($\ce{H2SO4}$) = $98.079\ \mathrm{g}\cdot \mathrm{mol}^{-1}$
$\frac{5000\,\mathr... |
Phosgene ($\ce{O=CCl2}$) is a potent toxin and in no way would I consider it a safe or even standard laboratory reagent (at least on an undergraduate level).
Allow me to lead you down the garden path of organic synthesis.
We have a haloalkane. What do we know about such compounds; they have a polarised C-X bond (... |
I have read numerous online questions similar to the one I am about to ask. But for most of them the answer has been that the reason one can add water to the unknown concentration solution during a titration is because:
1. Water has a pH of 7
2. This is a volumetric analysis, so as long as one record the volume o... |
Raoults law: Is the molar fraction the molar fraction in the entire system? |
The addition of $\ce{HBr}$ to $\ce{CH2=CHBr}$ produces $\ce{CH3-CHBr2}$. Why is this so?
According to me, halogens have a stronger $-I$ effect than a $+M$ effect (for example a halogen substituent on benzene, deactivates the ring), and hence the $\ce{CH3-CHBr+}$ carbocation should be more **unstable** as compared to... |
$\ce{S6}$, $\ce{S8}$, $\ce{S12}$ – does it make a difference or is it just a trick to make the question more complicated than it is?
What you know for sure is:
- $M(\ce{S}) = 32.065\ \mathrm{g}\cdot \mathrm{mol}^{-1}$
- $M(\ce{H2SO4}) = 98.079\ \mathrm{g}\cdot \mathrm{mol}^{-1}$
$\frac{5000\,\mathrm{g}}{... |
We have a drinking bottle made partly from **polypropylene** that wraps when washed in a **dishwasher**. We would like to change the plastic type so that it can withstand in dishwasher.
I know for a fact that my dishwasher at home has a lining inside made from polypropylene. After googling this I have found a few s... |
Which plastic type is used inside dishwashers? |
Two questions:
First, how does the gate provide a positive charge by running a current through it? I really just don't see how this positive charge could be achieved, unless you had some sort of battery in the gate itself and attached a wire to donate some of the electrons flowing through to the cathode of some oth... |
Transistors: How does the gate work? |
I wrote this long answer to a question which was deemed "duplicate" but really asked a more specific question, why there are the gaps in the periodic table etc.
> http://chemistry.stackexchange.com/questions/28769/organisation-in-periodic-table
The elements are organized in groups (the columns) because the elemen... |
We have a drinking bottle made partly from **polypropylene** that wraps when washed in a **dishwasher**. We would like to change the plastic type so that it can withstand in dishwasher.
I know for a fact that my dishwasher at home has a lining inside made from polypropylene. After googling this I have found a few s... |
can we add calcium ion as impurity in nacl crystal to get vacany defect? |
I was just reading about defects and doping in solids and read about the defect in ionic crystal ($\ce{NaCl}$). There were examples of $\ce{CrCl2}$. Could this also occur with $\ce{CaCl2}$? |
can we add calcium ion as impurity in NaCl crystal to get vacancy defect? |
I was just reading about defects and doping in solids and read about the defect in ionic crystal ($\ce{NaCl}$). There were examples of $\ce{SrCl2}$. Could this also occur with $\ce{CaCl2}$? |
I don't if it is a right place to ask this but; Is there any kind of paper or thin material, into what, after freezing it up in refrigerator, if you blow cool air, it will cool it (the air) up and pass it to other side as more cool?
EDIT: Is this a clearer version of your question?
Is there a porous thin material... |
I was just reading about defects and doping in solids and read about the defect in ionic crystal ($\ce{NaCl}$). There were examples of $\ce{SrCl2}$. Could this also occur with $\ce{CaCl2}$? |
Transition elements are good catalysts because they have multiple oxidation states?Why multiple oxidation states matter? |
Why are multiple oxidation states useful for a catalyst? |
For example, take 2,3 dimethylbutane for example. Why do we add the numerical multiplier 'di' when we've explicitly mentioned two locations?
It seems highly counter-intuitive to me. If I had no knowledge of this particular naming convention, I would intuitively assume that there were two 'dimethyl groups' (yes, tha... |
Why do we insert a numerical multiplier after group positions when naming an isomer? |
For example, take 2,3 dimethylbutane for example. Why do we add the numerical multiplier 'di' when we've explicitly mentioned two locations?
It seems highly counter-intuitive to me. If I had no knowledge of this particular naming convention, I would intuitively assume that there were two 'dimethyl groups' (yes, tha... |
For example, take 2,3 dimethylbutane for example. Why do we add the numerical multiplier 'di' when we've explicitly mentioned two locations? Why not just use 2,3 methylbutane?
It seems highly counter-intuitive to me. If I had no knowledge of this particular naming convention, I would intuitively assume that there w... |
> For example, take 2,3 dimethylbutane for example. Why do we add the numerical multiplier 'di' when we've explicitly mentioned two locations? Why not just use 2,3 methylbutane?
Actually, it is the other way round. Multiplicative prefixes (di, tri, tetra, etc.) are always used in names to denote multiplicity of ide... |
The way to determine the volume of an atom in a molecule (Therefore, the molecular volume) is by doing a quantum calculation to obtain the wave function and, then, integrate it.
You can obtain the volume of your desire molecule by following these steps:
1. Do a quantum calculation with the desire method and a ve... |
The way to determine the volume of an atom in a molecule (Therefore, the molecular volume) is by doing a quantum calculation to obtain the wave function and, then, integrate it.
You can obtain the volume of your desire molecule by following these steps:
1. Do a quantum calculation with the desire method and a ve... |
>The way to do obtain the charge of a fragment in a molecule is quiet similar to [How to calculate molecular volume from the wavefunction?][5].
As just repost the answer given over there and just editing the correct words to this post:
The way to determine the charge of a fragment in a molecule is by doing a quan... |
I know, The primary function of a salt bridge is to complete the circuit, so that charge can flow from one half-cell to the other. The second function is to balance the mass by allowing the anions to move to the half-cell where addition cations are being produced.But I can't seem to figure out what would happen if the... |
Describe the function of a salt bridge, What would happen if the half-cell compartments of a galvanic cell were not connected? |
My electrochemical knowledge is a wee bit rusty, but I believe the salt bridge helps balance the **charges** and not mass.
What charge you ask? So, let imagine you start up your galvanic cell (below). Electrons from the Zn move to Cu electrode. You start to build up a negative charge on the Cu which would resist/rep... |
My Chemistry book says that delocalised electrons are the reason for electrical conductivity in a metal.However it says that nonmetals like Sulphur,phosphorus and Silicon have "low" conductivity. How can they conduct electricity if they have no delcoalised electrons.Silicon has a giant macromolecular structure.While Su... |
Why isn't conductivity of non-metals zero? |
Is it possible to dope Ca ions in an NaCl crystal to produce a vacancy defect? |
My chemistry book says that delocalized electrons are the reason for electrical conductivity in a metal. However it says that nonmetals like sulfur, phosphorus and silicon have "low" conductivity. How can they conduct electricity if they have no delocalized electrons? Silicon has a giant macromolecular structure while ... |
Why is the conductivity of non-metals not equal to zero? |
Solomons and Fryhle has an example in which they have showed a very simple substitution reaction. The question was to synthesize methyl iodide. What they have done is taken methyl chloride and produced methyl iodide in the presence of NaI and ethanol through an SN2 mechanism. My question is -why did they use ethanol? I... |
Why does boron trifluoride form boron tetrafluoride ion instead of boron pentafluoride ion? |
This is the mechanism given in my lecture handout:
![enter image description here][1]
[1]: https://i.stack.imgur.com/7w5ol.png
I have a problem with the third species along. Surely the negatively charged oxygen would protonate before the other oxygen would. Also, why does this reaction work at all? The amine... |
> Surely the negatively charged oxygen would protonate before the other
> oxygen would.
Most of the time, but not all of the time.
> The amine group is more basic than the "alcohol group" that must leave
> to form the amide so why wouldn't that protonate first and then just
> leave (i.e no reaction)?
Most o... |
What type of dash does one use when indicating something like F$^{-}$? I assumed it was a minus, since you indicate positive charge with a +, but there is one professor I know who insists that it should be typeset with an endash. Is there a style manual on chemical typesetting I can consult. |
Proper dash to use in $^{-}$? |
>The way to do obtain the charge of a fragment in a molecule is quiet similar to [How to calculate molecular volume from the wavefunction?][1].
The way to obtain the wave function from GAMESS is with the AIMPAC keyword. Look at page 2-18 of [the GAMESS manual][2]
As just repost the answer given over there and jus... |
The way to determine the volume of an atom in a molecule (Therefore, the molecular volume) is by doing a quantum calculation to obtain the wave function and, then, integrate it.
The way to obtain the wave function from GAMESS is with the AIMPAC keyword. Look at page 2-18 of [the GAMESS manual][2]. :D
You can obta... |
which conformer stable of piperazine, when hydrogen of N in axial or in equatorial, or lone pair? why? |
I think I've heard hardening is when you dunk red-hot metal into cold water, and tempering is when you take that hardened metal, heat it slightly, and then let it cool slowly. However what is the difference between their end products? |
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