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Why do the bond dissociation energies of the O-H bonds in water differ? Is it related to an increase in lone pair-bond pair repulsions upon the breaking of the first O-H bond (decrease in stability, so lesser energy is required to break the bond)?
Bond dissociation energy of the first O-H bond: 502kJ/mol
Bond dis... |
In many textbooks, it is written that:
> The value of rate constant depends on the nature of the reactants, temperature and catalyst. It is independent of the concentration of the reactants.
However, the unit of the rate constant is
$$\left(\frac{\mathrm{mol}}{\mathrm{l}}\right)^{1-n} \mathrm{s}^{-1}$$
wher... |
In many textbooks, it is written that:
> The value of rate constant depends on the nature of the reactants, temperature and catalyst. It is independent of the concentration of the reactants.
However, the unit of the rate constant is
$$\left(\frac{\mathrm{mol}}{\mathrm{l}}\right)^{1-n} \mathrm{s}^{-1}$$
wher... |
Why do the bond dissociation energies of the O−H bonds in water differ? Is it related to an increase in lone pair-bond pair repulsions upon the breaking of the first O−H bond (decrease in stability, so lesser energy is required to break the bond)?
Bond dissociation energy of the first O−H bond: 502 kJ/mol
Bond di... |
Was at Dreamhack MTL this weekend and realised that in the whole venue there seems to be just a little bit of smoke in the spotlights and other light sources.
You also see that kind of smoke in shows and conventions. So I was wondering is that smoke something that gets piped in for that volumic effect on the lights,... |
Smoky lights at events - Piped in or a chemistry reaction of some kind? |
I recently setup a heating apparatus for the large antechamber in my glovebox (i.e., large amounts of heating tape). Eventually, I want to do bake-outs for my moisture-sensitive chemistries (e.g., battery electrolytes).
What is the standard procedure for bake out in an antechamber? I know that many commercial entiti... |
I was performing some experiments in Chemistry Lab today in which I had to find the functional groups present in a compound.
It being a very basic undergraduate course introducing us to the Chemistry lab, the functional groups were quite basic, and we just worked with mono-functional group compounds, including Carb... |
Why do some compounds which don't have the carbonyl group give positive 24DNPH Tests? |
Given some plant ash containing Silica and Sulfur, we need to find a way to extract the silica and sulfur using only techniques and resources available to a primitive person stuck on an island, with access to a forest, lake, and coal vein.
I've imagined a way to extract the silica, but I am not sure if it would work... |
Given some plant ash containing silica and sulfur, we need to find a way to extract the silica and sulfur using only techniques and resources available to a primitive person stuck on an island, with access to a forest, lake, and coal vein.
I've imagined a way to extract the silica, but I am not sure if it would work... |
I was looking through the following presentation:
http://folk.uio.no/helgaker/talks/SostrupIntegrals_10.pdf
Looking at the section on 4-electron integrals, I couldn't help but notice that the slides wrote that the 4-electron terms (Kij and Jij) were Gabcd x Dcd. [see slide 25]
I realised that Dcd was referring... |
Given some plant ash containing silica and sulfur, we need to find a way to extract the silica and sulfur using only resources available to a primitive person stuck on an island, with access to a forest, lake, and coal vein. (This is part 2 of my Primitive Technology series. [Part 1](https://chemistry.stackexchange.com... |
Why do some compounds without carbonyl group give positive 2,4-DNPH test? |
I was reading about the various ways to optimise the geometry of the system, and found that none of the sources mention how the Hessian matrix is obtained.
How does one obtain the Hessian matrix? I’m thinking it’s either some analytical formula or just numerical differentiation. |
How is the Hessian evaluated? |
I'm trying to make a single e-paper capsule (1cm x 1cm) at home. At first, I tried to charge the TiO2 particles by putting them in H2O with NaOH and then putting that whole solution in baby oil, but it turns out I shouldn't have any water in the whole process. I also tried adding a surfactant (liquid soap) but it also ... |
How to charge TiO2 particles for a DIY e-paper capsule? |
In the laboratory notes it is indicated that it is ill advised to eat the solid formed from this experiment. An esterification reaction, in which salicylic acid is treated with acetic anhydride.
If it is for the acid added as catalyst either sulfuric acid or phosphoric acid. Why isn't it possible to neutralize it wi... |
I'm trying to make a single e-paper capsule (1 cm × 1 cm) at home. At first, I tried to charge the $\ce{TiO2}$ particles by putting them in $\ce{H2O}$ with $\ce{NaOH}$ and then putting that whole solution in baby oil, but it turns out I shouldn't have any water in the whole process. I also tried adding a surfactant (li... |
How to charge titanium dioxide particles for a DIY e-paper capsule? |
For a molecule to have a smell it's necessary that the molecule be volatile enough to be in the air. So I think that excludes molecules which are solid at room temperature & atmospheric pressure... maybe the question then is equivalent to: what is the highest molecular weight organic compound which is liquid at room te... |
What's the biggest organic molecule that could have a smell? |
### Question
> $\ce{CaCO3}$ dissociated in a closed system according to the reaction:
> $$\ce{CaCO3(s) -> CaO(s) + CO2(g)}$$
> Assuming the reaction is in thermodynamic equilibrium, what is/are the degree(s) of freedom?
### Doubt
I tried applying the condensed phase rule. All that I could arrive at was
... |
Since latent heat is not sensible, it seems like it would be useful in creating an efficient battery. Sensible heat interferes with electron flow in standard lead-acid and other batteries. The latent heat-electron interface might occur separately from the energy storage. Has this idea been explored? |
Why not create a latent heat battery? |
How to predict the decomposition products of for example barium carbonate? |
For a molecule to have a smell it's necessary that the molecule be volatile enough to be in the air. So I think that excludes molecules which are solid at room temperature and atmospheric pressure. Maybe the question then is equivalent to: what is the highest molecular weight organic compound which is liquid at room te... |
**Unless you worked to Pharma industry Good Manufacturing Practice you shouldn't trust your product**
The simple reason why you should not trust the product is that that you don't know it is safe unless you have followed rigorous quality control processes. The drug industry follows carefully regulated quality-contro... |
A student in Chemistry StackExchange asked the effect of radio waves on matter, which led to an interesting set of arguments by some users. It was pointed out that in a proton nuclear magnetic resonance (or any other nuclei for that matter), there is no absorption of the photon corresponding to the radio waves. The fol... |
Radiofrequency transmitter in an NMR experiment: Is there an involvement of (electromagnetic) radio wave? |
By applying the logic that phenol exists in enol form rather than keto form as it attains aromatic character, why is it not the case in coumarins ?
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/PsQ8H.png |
Why coumarin predominantly exists in keto form? |
If I have varsol in a tank and methanol is put into the same tank will methanol rise to the top or will it separate? Or will it mix together ?
|
[Varsol alias White spirit][1], used as a painting solvent, is based on C9-C12 oil hydrocarbons, with density 0.765(type T1)-0.795(type T3)
[Methanol][2] has density 0.792. So it would rather sink under T1, or being indecisive with T3 ( this may be temperature dependent )
Note that methanol has very limited solubilit... |
By applying the logic that phenol exists in enol form rather than keto form as it attains aromatic character, why is it not the case in coumarins ?
[![enter image description here][1]][1]
[![enter image description here][2]][2]
[1]: https://i.stack.imgur.com/PsQ8H.png
[2]: https://i.stack.imgur.com/8a... |
If the total number of atoms in a sample of potassium dichromate is $2.13\cdot10^{24}$ , then the amount of chromium in this sample is?
the answer that I've come up with is $367.64\ \mathrm g$
but in fact the solution in my book is $33.4\ \mathrm g$. |
I'm trying to make a single e-paper capsule (1 cm × 1 cm) at home. At first, I tried to charge the $\ce{TiO2}$ particles by putting them in $\ce{H2O}$ with $\ce{NaOH}$ and then putting that whole solution in baby oil, but it turns out I shouldn't have any water in the whole process. I also tried adding a surfactant (li... |
Most of the reactions undergo ring expansion whenever favourable.
But this reaction doesnt seems to do so.
Could anybody explain why? ( Source: Craig B Fryhle and Solomon)
 |
Most of the reactions undergo ring expansion whenever favourable.
But this reaction \[1, p. 514\] doesn't seems to do so:
> **Practice Problem 11.18** Provide a mechanism for the following reaction.
> [![Reaction between (1‐methoxyethyl)cyclopentane and HCl][1]][1]
Could anybody explain why?
### References... |
[$\ce{Mg(NO3)2}$][1] has (Figure 1):
- One $\ce{Mg}$ atom
- Two $\ce{NO3}$ groups, which are composed of:
- One $\ce{N}$ atom
- Three $\ce{O}$ atoms
[![Magnesium nitrate][2]][2]
**Figure 1**: we have one $\ce{Mg}$, two $\ce{N}$ ($2 \times 1$) and six $\ce{O}$ ($2 \times 3$) in $\ce{Mg(NO3)2}$.
Now al... |
[Varsol alias White spirit][1], used as a painting solvent, is based on C9-C12 oil hydrocarbons, with density 0.765(type T1), 0.780(type T2), 0.795(type T3)
[Methanol][2] has density 0.792. So it would rather sink under T1, T2, or being indecisive with T3 ( this may be temperature dependent )
Note that methanol has v... |
Because chemists learned that the atom was divisible, did Dalton's theory get any criticism or did they just adjust the theory to fit the new idea? |
Did the finding of the electron from cathode rays/ oil drop experiment at least temporarily throw Dalton's Atomic theory "out the window"? |
1.034 g of a metal sulfate hydrate was heated to a high enough temperature to remove all the water of hydration. The mass of the anhydrous salt left behind was found to be 0.956 g. What is the mass percentage of water in the hydrate?
I did $1.034-0.956=0.078$ grams of water
Then I did $\frac{0.078}{1.034}$= about... |
Mass percentage of water in hydrate? |
Dalton's atom was the most primitive idea. Keep in mind many physicists were against atomistic theory and cathode rays were not immediately recognized as electrons or a subatomic particles. The beauty of science is that it is self-correcting. This happens on daily basis still today. Nobody actually throws any theory ou... |
Note that I have never heard about Varsol until now, living in the Central Europe. By searching Wikipedia ( what you could do as well before asking ), I realized the below:
[Varsol alias White spirit alias many other synonyms][1], used as a painting solvent, is based on C9-C12 oil hydrocarbons, with density 0.765(type... |
Why is the product of the reaction "Bi + O2" Bi2O3 instead of Bi2O5? |
At first I thought that the reason is what I was taught, the absence of vacant d-orbitals but then I did some research. Most of the answers stated what I initially thought but one particular answer told that it's a common misconception (d-orbital theory). According to it, there can be two possible reasons-
1. Not mu... |
Why can't O form OF6? |
Consider some liquid in a beaker. I am measuring its temperature using a thermometer. When i put my thermometer's bulb in the liquid, the particles of the bulb gain the same kinetic energy as of the liquid particles. Now, my question is that
Do the particles of thermometer's bulb attain the same translational, rotatio... |
Note that I have never heard about Varsol until now, living in the Central Europe. By searching Wikipedia ( what you could do as well before asking ), I realized the below:
[Varsol alias White spirit alias many other synonyms][1], used as a painting solvent, is based on C7-C12 oil hydrocarbons, with density 0.765(type... |
Why does the addition of carbon dioxide to calcium hydroxide create the precipitate calcium carbonate? What happens chemically for such a molecule to form? |
Why does bubbling carbon dioxide through calcium hydroxide result in a precipitate? |
One possible explanation involves atomic size. You need a large enough atom in the middle to stabilize all the occupied orbitals in the cathedral arructure; sulfur makes it but oxygen does not.
[This reference published by the University of British Columbia](https://www.google.com/url?sa=t&source=web&rct=j&url=http... |
One possible explanation involves atomic size. You need a large enough atom in the middle to stabilize all the occupied orbitals in the cathedral arructure; sulfur makes it but oxygen does not.
[This reference published by the University of British Columbia](https://www.google.com/url?sa=t&source=web&rct=j&url=http... |
One possible explanation involves atomic size. You need a large enough atom in the middle to stabilize all the occupied orbitals in the cathedral arructure; sulfur makes it but oxygen does not.
[This reference published by the University of British Columbia](https://www.google.com/url?sa=t&source=web&rct=j&url=http... |
According to the $2n^2$ rule, the fifth shell should accommodate 50 electrons.
However, my chemistry book says that the $2n^2$ rule does not apply to the fifth shell.
Could you explain why this happens?
P.S. I have studied quantum numbers, Heisenberg uncertainty principle, Pauli exclusion principle, and the qu... |
[![enter image description here][1]][1]
With reference to the phase diagrams drawn in b and d why are the Gibbs phase lines coming closer from being so further apart?
[1]: https://i.stack.imgur.com/VGRxk.jpg |
Why are the phase diagrams showing $G_s$ and $G_l$ situated so close on one end and then widens up at the other extremes? |
the textbooks say that it is the amount of electrons lost or gained by an atom in a bond but in a covalent molecule the atoms never technically lose electrons ,instead share them to in such a way to complete their octet.for eg:- In OF2 molecule, it is said that the oxidation state of oxygen is +2 which implies it has l... |
What exactly is "oxidation state"? |
One possible explanation involves atomic size. You need a large enough atom in the middle to stabilize all the occupied orbitals in the octahedral structure; sulfur makes it but oxygen does not.
[This reference published by the University of British Columbia](https://www.google.com/url?sa=t&source=web&rct=j&url=htt... |
One possible explanation involves atomic size. You need a large enough atom in the middle to stabilize all the occupied orbitals in the octahedral structure; sulfur makes it but oxygen does not.
[This reference published by the University of British Columbia](https://www.google.com/url?sa=t&source=web&rct=j&url=htt... |
How to calculate size of a specific cavity in a protein for every frame in trajectory file? |
In my high school chemistry class we are writing a lab. Originally, I wanted to measure the rate of a ligand exchange reaction at different temperatures by measuring changes in conductivity. After some discussion, I came to the conclusion that there would be no change in conductivity and therefore I would not be able t... |
In my high school chemistry class we are writing a lab. Originally, I wanted to measure the rate of a ligand exchange reaction at different temperatures by measuring changes in conductivity. After some discussion, I came to the conclusion that there would be no change in conductivity and therefore I would not be able t... |
In my high school chemistry class we are writing a lab. Originally, I wanted to measure the rate of a ligand exchange reaction at different temperatures by measuring changes in conductivity. After some discussion, I came to the conclusion that there would be no change in conductivity and therefore I would not be able t... |
In my high school chemistry class we are writing a lab. Originally, I wanted to measure the rate of a ligand exchange reaction at different temperatures by measuring changes in conductivity. After some discussion, I came to the conclusion that there would be no change in conductivity and therefore I would not be able t... |
Since oxygen is more electronegative than chlorine, if I introduce $\ce{O2}$ gas to $\ce{AlCl3}$ and apply some heat, will the chlorine be replaced by oxygen, resulting in $\ce{AlO3}$ or $\ce{AlClO2}$, then evolving the remaining $\ce{Cl2}$ into the air? Why not? |
Since oxygen is more electronegative than chlorine, if I introduce $\ce{O2}$ gas to $\ce{AlCl3}$ and apply some heat, will the chlorine be replaced by oxygen, resulting in $\ce{Al2O3}$ or $\ce{AlClO2}$, then evolving the remaining $\ce{Cl2}$ into the air? I suspect not, but why?
Is there a standard way of converting... |
Since oxygen is more electronegative than chlorine, if I introduce $\ce{O2}$ gas to $\ce{AlCl3}$ and apply some heat, will the chlorine be replaced by oxygen, resulting in $\ce{Al2O3}$ or $\ce{Al2(ClO2)3}$, then evolving the remaining $\ce{Cl2}$ into the air? I suspect not, but why?
Is there a standard way of conver... |
Is it possible to tell just by looking(reaction's equation) that whether a given is reaction is elementary or non elementary ? |
Since oxygen is more electronegative than chlorine, if I introduce $\ce{O2}$ gas to $\ce{AlCl3}$ and apply some heat, will the chlorine be replaced by oxygen, resulting in $\ce{Al2O3}$ or $\ce{Al(ClO2)3}$, then evolving the remaining $\ce{Cl2}$ into the air? I suspect not, but why?
Is there a standard way of convert... |
In my high school chemistry class we are writing a lab. Originally, I wanted to measure the rate of a ligand exchange reaction at different temperatures by measuring changes in conductivity. After some discussion, I came to the conclusion that there would be no change in conductivity and therefore I would not be able t... |
You might want to raise the temperature a little bit as the reaction proceeds at 100-110°C to form formic acid. If the temperature is further raised to 260-280°C, then the reaction will proceed to form allyl alcohol.
[![enter image description here][1]][1]
[![enter image description here][2]][2]
Formic acid ha... |
How do halogens get their colour? |
**Reactions that are probably not elementary**
Whenever there are more than three reactants, it is unlikely that the reaction is elementary. Tenary elementary reactions are already quite rare. If you have a reaction like
$$\ce{2C8H18 + 25 O2 -> 16 CO2 + 18 H2O}$$
it is impossible for 27 particles to come toget... |
> Do the particles of thermometer's bulb attain the same translational, rotational and vibrational energy (vibration of atoms within a particle) as of the particles of the liquid?
No, but they will have the same temperature. Solids don't have any translational energy, the atoms time-averaged positions are constant. ... |
We had a question in a rest comparing the bond lengths of hydrocarbons fluorides, and the answer key says CF3- CF3's supposed to have a longer C-C bond than H3C- CH2--F.
Why is this so? Wouldn't the C-F bond have less s-character, leading to increase in s-character in the other bonds? That way, CF3-CF3 should have t... |
Why does the addition of carbon dioxide to calcium hydroxide create the precipitate calcium carbonate? What happens chemically for such a molecule to form? How exactly do their interactions come into play?
Now CaOH isn’t terribly soluble in water but the parts that do dissolve, disassociate into their respective OH<... |
As other answers have noted, the only gas lighter than helium is hydrogen, which has some [flammability issues][1] that make it more difficult to handle safely than helium.
Also, in practice, hydrogen is not significantly "lighter" than helium. While the molecular mass (and thus, per the [ideal gas law][2], the den... |
The answer is as simple as it will be unhelpful to your original question: There is no tautomer possible.
Coumarin does not have a keto group, and there are no enolisable protons either. Coumarin consists of a benzene ring, connected to a heterocycle with the functional group lactone. The molecule is flat and the c... |
> Do the particles of thermometer's bulb attain the same translational, rotational and vibrational energy (vibration of atoms within a particle) as of the particles of the liquid?
No, but they will have the same temperature. Solids don't have any translational energy, the atoms time-averaged positions are constant. ... |
**Dalton's theory was about how atoms behaved: the observation of Cathode rays provided part of the explanation of *why* they behaved like this**
The key elements of Dalton's theory were observational. He explained how the idea of atoms could explain chemical reactions and many observational facts about them. This w... |
By applying the logic that phenol exists in enol form rather than keto form as it attains aromatic character, why is it not the case in coumarin?
[![structure of coumarin][1]][1]
[![keto and enol form of coumarin][2]][2]
[1]: https://i.stack.imgur.com/PsQ8H.png
[2]: https://i.stack.imgur.com/8a7Fw.jpg |
Why does coumarin predominantly exist in keto form? |
I wrote a piece of code on RHF using Python a while back, and figured I'd extend it to also implement CNDO/2 (yes, I know it's old but I figured it'd be easier for me.)
The approximated Fock matrix elements, taken from the original paper, are as follows:
$$F_{\mu\mu} = U_{\mu\mu} + [(P_{AA} - Z_A) - 0.5(P_{\mu\m... |
Suppose that i have some gas of which the critical temperature is 20°C. Does it mean that how high pressure i apply on the gas, it is not going to turn into a liquid above 20°C? But why so? I think that anything is a liquid if the particles of that substance have got close enough i.e. the space between the particles is... |
**Reactions that are probably not elementary**
Whenever there are more than three reactants, it is unlikely that the reaction is elementary. Tenary elementary reactions are already quite rare. If you have a reaction like
$$\ce{2C8H18 + 25 O2 -> 16 CO2 + 18 H2O}$$
it is impossible for 27 particles to come toget... |
How do elemental halogens get their colour? |
I wrote a piece of code on RHF using Python a while back, and figured I'd extend it to also implement CNDO/2 (yes, I know it's old but I figured it'd be easier for me.)
The approximated Fock matrix elements, taken from the original paper, are as follows:
$$F_{\mu\mu} = U_{\mu\mu} + [(P_{AA} - Z_A) - 0.5(P_{\mu\m... |
I am trying to model the interaction between an electrode and a saline solution through an RC circuit.
<!-- Begin schematic: In order to preserve an editable schematic, please
don't edit this section directly.
Click the "edit" link below the image in the preview instead. -->
The approximated Fock matrix elements, taken from the original paper, are as follows:
$$F_{\mu\mu} = U_{\mu\mu} + [(P_{AA} - Z_A) - 0.5(P_{\mu\m... |
In this [source](https://www.cpp.edu/~psbeauchamp/pdf/314_conformations.pdf), it is possible to calculate conformational energy from Newman projections. How to calculate the conformational energy so I can obtain the values similar to the values from the source? |
I am trying to find chiral centers of molecules in QM9 dataset. Browsing their SMILES representation, I noticed SMILES yield using
datasets.get_qm9(GGNNPreprocessor(), return_smiles=True)
don't have `@` or `@@`, but it seems that some of these molecules have alternative representations. For instance, both 'Cc1cc... |
Enantiomeric excess is defined as
$$ee = \frac{[R]-[S]}{[R]+[S]}$$
I found this problem in an IChO paper:
"When using the enantiomerically pure (BINOL)Al(OiPr) as a catalyst for reduction of αbromoacetophenone, the ee of the product equals 81%. What is the ee of the product if the catalyst ee equals 50%?"
... |
In this [source](https://www.cpp.edu/~psbeauchamp/pdf/314_conformations.pdf), the conformational energy from Newman projections is obtained. Is there a formula or quantum chemistry approach to obtain the values in first place (pretend that I don't know the source)? |
The Wikipedia structure is:
<img src="https://i.stack.imgur.com/MQAiw.png" width="240" height="168">
Note the empty bond at far-right.
"Journals on the Web" has:
<img src="https://i.stack.imgur.com/OSLVH.gif" width="202" height="96">
CH3 added at far-right.
And rxlist.com shows:
<img src="https://i... |
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