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Can aromatic compounds travel through metal boards and glass? |
> Degrees of freedom describe the different ways atoms move in a sample.
The classical equations of motion for a system of N atoms describe the time evolution of 3N positions and 3N momentum coordinates for the atomic nuclei (ignoring electronic degrees of freedom). The total energy is a function of those 6N degrees... |
In "*NCERT Chemistry for Class XI - Volume II*", in chapter "*s-block elements*", under the topic "*Chemical Properties of **alkali metals***", it is given:
[![enter image description here][1]][1]
In the last set of lines, it is given that in concentrated solution, the blue colour changes to bronze colour and the... |
Why does concentration of solutions of alkali metals in liquid ammonia change the magnetic properties? |
At equilibrium
$$
\begin{align}
K &= \exp\left(\cfrac{TΔS^\circ - ΔH^\circ}{RT}\right)\\
⇒ \frac{\mathrm d \ln K}{\mathrm dT} &= \frac{ΔH^\circ}{RT^2}
\end{align}
$$
If enthalpy change is positive, change in $\ln K$ w.r.t. $T$ is positive. Hence, $\ln K$ and therefore $K$ increase (position of equilibrium sh... |
Can aroma compounds travel through metal boards and glass? |
A friend from customs said "if drugs have been in a glass jar for more than a day, the aroma compounds travel through the lid and the dog can detect it, especially after 2-3 days. They can travel through almost any material given enough time"
If you decanted freezing perfume into a very cold jam-jar and washed it it... |
In "*NCERT Chemistry for Class XI - Volume II*", in chapter "*s-block elements*", under the topic "*Chemical Properties of **alkali metals***", it is given:
[![enter image description here][1]][1]
In the last set of lines, it is given that in concentrated solution, the blue colour changes to bronze colour and the... |
Somebody I know insists that the use of a catalyst increases the atom economy. They did chemistry at school, and were told that a catalyst increases the atom economy. He pointed me to several past exams where this was written as a valid answer in mark schemes.
However, I am convinced that this is false. After all, a... |
In "*NCERT Chemistry for Class XI - Volume II*", in chapter "*s-block elements*", under the topic "*Chemical Properties of **alkali metals***", it is given:
> ***(vi) Solutions in liquid ammonia***: The alkali metals dissolve in liquid ammonia giving deep blue solutions which are conducting in nature.
> $$\ce{M +... |
Consider the reaction
$$\ce{A(g) + H2O(l) <=> B(aq) + C(g)}$$
If all gases and solutions were ideal, the standard state would be pure water, the solute B at a concentration of 1 M, the gases A and C each at a pressure of 1 bar, and the system at a pressure of 1 bar.
For non-ideal gases and solutions, it would ... |
Water is pooling in my garden next to my neighbour's fence. He has been harassing us in multiple ways for 8 years.
It is the only place on my property where this is happening. It has never happened like this before until last year.
Last year, in the driest summer we have had in years, we saw my neighbour had a ho... |
Gold is commonly used in mobile phones as an electrical conductor,as it is apparently better than copper at conducting electricity
Quoting from extremetech.com :
"The materials recovered are reused in new electronics parts and the gold and other precious metals are melted down and sold as ingots to jewelers and i... |
**Yes, you're exactly right - multiple papers in chemistry ML drop the units.**
There are even comparisons (usually by statistics, ML or comp. sci. researchers) where models are compared by "averaging" errors down a column like that. Of course that's meaningless, since you can't average electron volts or Hartree (en... |
Due to circumstance, our Data Centre build has some delays and it currently looks like we're going to have to perform a hydrostatic test of our sprinkler system _with live computers in it_.
As I have an education as a chemist, _but haven't done any serious chemistry in >30 years_ I thought of using another liquid th... |
Can pure (or roughly pure) $\ce{Al}$ be somehow thermally or chemically separated from $\ce{Si}$ contained in an $\ce{Al-Si}$ alloy? How? Approximately what purity of Aluminum can be achieved in this way? |
Can pure (or roughly pure) $\ce{Al}$ be somehow thermally, chemically, or physically separated from the $\ce{Si}$ contained in an $\ce{Al-Si}$ alloy? How? Approximately what purity of Aluminum can be achieved in this way? |
I have seen several sources note that wood ash typically contains 3-4% $\ce{SO3}$ by weight. My question is, why would ash have any $\ce{SO3}$? $\ce{SO3}$ boils at 45c so it should have all boiled away by the time the wood turned to ash |
This is a question from a 7th grade chemistry class.
>Why does adding salt ($\ce{NaCl}$) to a cucumber soup makes it taste more sour?
My best guess is that the salt affects the dissociation levels of acids in the cucumbers - adding $\ce{NaCl}$ shifts the balance and more $\ce{H+}$ is being released, but I don't th... |
I have seen several sources note that wood ash typically contains 3-4% $\ce{SO3}$ by weight. My question is, why would ash have any $\ce{SO3}$? $\ce{SO3}$ boils at 45c so it should have all boiled away by the time the wood turned to ash
Some sources for wood ash composition:
[Source 1](https://digitalfire.com/4si... |
The reaction of the ketal **1** with aqueous H<sub>2</sub>SO<sub>4</sub> is most likely to follow the pathway **1** --> **2** --> **3** to form α,β-unsaturated ketone **3**. This is a typical ketal hydrolysis in acid medium. For the proposed reaction pathway **1** --> **4** --> **5** --> **6**, species **6**... |
We have the following chemical reactions.
$$A+B^{*} \rightarrow C + D^{*}$$
$$D^{*} \rightarrow B^{*} + B^{*}$$
$$B^{*} \rightarrow B$$
The question is whether the system is explosive if the initial concentrations are $[A]=100 \cdot 10^{-6} mol/cm^3$ and $[B]=1 \cdot 10^{-6} mol/cm^3$? We know that $k_1=10^6 cm... |
We have the following chemical reactions.
$$A+B^{*} \rightarrow C + D^{*}$$
$$D^{*} \rightarrow B^{*} + B^{*}$$
$$B^{*} \rightarrow B$$
The question is whether the system is explosive if the initial concentrations are $[A]=100 \cdot 10^{-6} mol/cm^3$ and $[B]=1 \cdot 10^{-6} mol/cm^3$? We know that $k_1=10^6 cm... |
### Question
> We have the following chemical reactions:
> $$
\begin{align}
\ce{A + B^* &-> C + D^*}\tag{1}\\
\ce{D^* &-> B^* + B^*}\tag{2}\\
\ce{B^* &-> B}\tag{3}
\end{align}
$$
> The question is whether the system is explosive if the initial concentrations are $[\ce{A}] = \pu{100e-6 mol cm-3}$ and $[\c... |
A given amount of (liquid) water in an open vessel is heated from 20 degree celsius to 50 degree celsius. Suppose it absorbs x joule in the process. What is the enthalpy change in the process? Is it = x J ? But many authors define enthalpy change as heat aborbed or emitted at constant temperature and pressure. And here... |
This post is inspired by [a question][1] regarding the meaning of off-diagonal elements of the KE matrix (in some AO basis). One answer suggests that a diagonalized KE matrix might not be very useful. I take the liberty of quoting:
> I am not sure it really makes sense to give much of an interpretation to this, howev... |
When one "arbitrarily" insists that the box is of a certain length, that is where any method fails. The molecular geometry provides the boundary conditions on the standing waves for the electrons, so people fix things by adding an extra length (fudge factor) to account for the discrepancy in the model. So, the Kekule... |
When one "arbitrarily" insists that the box is of a certain length, that is where any method fails. The molecular geometry provides the boundary conditions on the standing waves for the electrons, so people fix things by adding an extra length (fudge factor) to account for the discrepancy in the model. So, the Kekule... |
When one "arbitrarily" insists that the box is of a certain length, that is where any method fails. The molecular geometry provides the boundary conditions on the standing waves for the electrons, so people fix things by adding an extra length (fudge factor) to account for the discrepancy in the model. So, the Kekule... |
When one "arbitrarily" insists that the box is of a certain length, that is where any method fails. The molecular geometry provides the boundary conditions on the standing waves for the electrons, so people fix things by adding an extra length (fudge factor) to account for the discrepancy in the model. So, the Kekule... |
When one "arbitrarily" insists that the box is of a certain length, that is where any method fails. The molecular geometry provides the boundary conditions on the standing waves for the electrons, so people fix things by adding an extra length (fudge factor) to account for the discrepancy in the model. So, the Kekule... |
A given amount of (liquid) water in an open vessel is heated from 20 degree celsius to 50 degree celsius. Suppose it absorbs x joule in the process. What is the enthalpy change in the process? Is it = x J ? But many authors define enthalpy change as heat absorbed or emitted at constant temperature and pressure. And her... |
> Degrees of freedom describe the different ways atoms move in a sample.
The classical equations of motion for a system of N atoms describe the time evolution of 3N positions and 3N momentum coordinates for the atomic nuclei (ignoring electronic degrees of freedom). The total energy is a function of those 6N degrees... |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/Tlh4U.png
I have to write the four half cell reactions from the Latimer Diagram, which is a metal (M) in basic solution. I can only come up with the first half reaction, which I believe is:
MO_4^2- +e^- = MO_4^3-
But for the others I'... |
In electrolytic refining, the metals like Platinum and Gold are deposited as anode mud. Why aren't they deposited on the cathode since they have higher reduction potential? |
When one "arbitrarily" insists that the box is of a certain length, that is where any method fails. The molecular geometry provides the boundary conditions on the standing waves for the electrons, so people fix things by adding an extra length (fudge factor) to account for the discrepancy in the model. So, the Kekule... |
Q-Predict the most accurate structure of NCS- ?
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/K1s2F.jpg
<B>My Attempt</b><BR>
Formal Charge in ($1$) -
<br><B>N =$-1$ <BR>C = $0$<BR>S = $0$
<BR><BR></b>
Formal Charge in ($2$) -
<br><B>N =$-1$ <BR>C = $-2$<BR>S = $+2$
<b>Concl... |
Q-Predict the most accurate structure of $\ce{NCS-}$?
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/K1s2F.jpg
<B>My Attempt</b><BR>
Formal Charge in ($1$) -
<br><B>N =$-1$ <BR>C = $0$<BR>S = $0$
<BR><BR></b>
Formal Charge in ($2$) -
<br><B>N =$-1$ <BR>C = $-2$<BR>S = $+2$
<b... |
The reaction of the ketal **1** with aqueous H<sub>2</sub>SO<sub>4</sub> is more likely to follow the pathway **1** --> **2** --> **3** to form α,β-unsaturated ketone **3**. This is a typical ketal hydrolysis in acid medium. For the proposed reaction pathway **1** --> **4** --> **5** --> **6**, species **6**... |
> Predict the most accurate structure of $\ce{NCS-}.$
> $$\Large\underset{(\textbf{1})}{\ce{(:\!\!\overset{\huge.\!\!.}{N}=C=\overset{\huge.\!\!.}{\underset{\huge.\!\!.}{S}})-}}\qquad\underset{(\textbf{2})}{\ce{(\overset{\huge.\!\!.}{\underset{\huge.\!\!.}{C}}=S=\overset{\huge.\!\!.}{\underset{\huge.\!\!.}{N}})-}}$$... |
I gather that the equilibrium constant <i>K</i> = 1 implies that, at equilibrium, neither the forward nor the backward reactions are thermodynamically favoured. But if pressure of the system increases and this shifts the position of equilibrium, the value of <i>K</i> remains to be 1.
How then can <i>K</i> = 1 imply... |
I understand most of the theory behind TLC and that different volatile solvents have different polarities and cause the 'spotted' substances to move at different rates, but what is the point of creating mixtures and then using them in different ratios? How could the results change if I changed the ratios?
For exampl... |
Chromatography is really an empirical science. The fluid mechanical side and the adsorption phenomenon is somewhat well understood but choosing mobile phases is essentially based on trials, sadly to date. If someone has given you a ratio, say 8:2, it means someone must have tried it and they found that this mobile phas... |
My understanding is that in alkyl-substituted alkenes there is hyperconjugation between $(C−X)$ and $^∗(C=C)$. I also have read that more alkyl-substituted alkenes are many folds more reactive in addition reactions. I understand how hyperconjugation stabilizes alkyl-substituted carbocations.
However, based on the fa... |
If alkyl-substituted alkenes are more stable, how does one explain their increased addition reactivity? |
My understanding is that in alkyl-substituted alkenes there is hyperconjugation between $(\ce{C−X})$ and $^∗(\ce{C=C})$. I also have read that more alkyl-substituted alkenes are many folds more reactive in addition reactions. I understand how hyperconjugation stabilizes alkyl-substituted carbocations.
However, based... |
### Question
> We have the following chemical reactions:
> $$
\begin{align}
\ce{A + B^* &-> C + D^*}\tag{1}\\
\ce{D^* &-> B^* + B^*}\tag{2}\\
\ce{B^* &-> B}\tag{3}
\end{align}
$$
> If the initial concentrations are $[\ce{A}] = \pu{100e-6 mol cm-3}$ and $[\ce{B}] = \pu{1e-6 mol cm-3}$, is the system explo... |
In [electrolytic refining][1], metals like platinum and gold are deposited as anode mud.
Why aren't they deposited on the cathode since they have higher reduction potential?
[1]: https://en.wikipedia.org/wiki/Refining_(metallurgy)#Electrolytic_refining |
Electrolytic refining of precious metals — why the anode rather than the cathode? |
I have seen several sources note that wood ash typically contains 3–4 % $\ce{SO3}$ by weight. My question is, why would ash have any $\ce{SO3}$? $\ce{SO3}$ boils at 45 °C, so it should have all boiled away by the time the wood turned to ash.
Some sources for wood ash composition:
[Source 1](https://digitalfire.co... |
So the problem is in Last step . We get a relation between M and V but not much satisfactory data . What to do further. Is there an easier method? |
> $\pu{5.35 g}$ of a salt $\ce{ACl}$ is dissolved in $\pu{250 ml}$ of solution. The $\mathrm{pH}$ of the resultant solution was found to be $4.85.$ Find the ionic radius of $\ce{A+}$ and $\ce{Cl-}$ if density of $\ce{ACl}$ is $\pu{2.2 g cm-3}.$ Given
> $$\frac{r_+}{r_-} = 0.73 \qquad K_\mathrm{b} = \pu{2E-5}$$
S... |
I came across a research paper where relative rates of KOH and TlOH in suzuki coupling [![enter image description here][1]][1] reaction were compared.
thallium hydroxide increased the yield of products.Reaction also occured at room temperature as compared to KOH.
what would be the effect of Thallium hydroxide?
... |
Why Thallium Hydroxide increases yield of product in Suzuki reaction? |
I came across a research paper where relative rates of $\ce{KOH}$ and $\ce{TlOH}$ in Suzuki coupling reactions are compared.
<!-- Please insert a citation here -->
Thallium hydroxide increased the yield of products, see table below. The reaction also occurred at room temperature as compared to $\ce{KOH}$.
What is... |
Why does thallium hydroxide increase the yield of product in a Suzuki reaction? |
I came across a research paper by Uenishi et al. \[[1](https://doi.org/10/fhmqsr)\] where relative rates of $\ce{KOH}$ and $\ce{TlOH}$ in Suzuki coupling reactions are compared.
Thallium hydroxide increased the yield of products, see Table I below. The reaction also occurred at room temperature as compared to $\ce{... |
They say that enthalpy of reaction is the heat when at constant temperature and pressure. So if enthalpy=dU+PdV= TdS-PdV+PdV+MudN=TdS+MudN and heat is TdS then what happens to the chemical potential term if enthalpy is heat? |
They say that enthalpy of reaction is the heat when at constant temperature and pressure. So if enthalpy is
$$\mathrm dH = \mathrm dU + p\,\mathrm dV = T\,\mathrm dS - p\,\mathrm dV + p\,\mathrm dV + μ\,\mathrm dN = T\,\mathrm dS + μ\,\mathrm dN$$
and heat is $T\,\mathrm dS,$ then what happens to the chemical pot... |
> I gather that the equilibrium constant K = 1 implies that, at equilibrium, neither the forward nor the backward reactions are thermodynamically favoured.
There is nothing special about K = 1. At equilibrium, no matter the value of K, there is no net reaction. Forward and backward reactions proceed at the same spee... |
My first language is not English, so there might be some parts where it's hard to read. Sorry in advance.
----------
I have some questions regarding the derivation of the equilibrium constant and the rate-determining step.
For a hypothetical reaction
$$\ce{aA + bB <=> cC + dD}$$
the equilibrium constant ... |
> Predict the most preferable structure of $\ce{NCS-}.$
> $$\Large\underset{(\textbf{1})}{\ce{(:\!\!\overset{\huge.\!\!.}{N}=C=\overset{\huge.\!\!.}{\underset{\huge.\!\!.}{S}})-}}\qquad\underset{(\textbf{2})}{\ce{(\overset{\huge.\!\!.}{\underset{\huge.\!\!.}{C}}=S=\overset{\huge.\!\!.}{\underset{\huge.\!\!.}{N}})-}}... |
 did I name it right??
Please help me in naming dispiro compounds
|
1-chloro-2-methylpropane --> 2-chloro-2-methylpropane.
My understanding is that an E2 reaction produces two types of alkenes, the major product for non-sterically hindered bases is the more substituted product (Zaitsev) while the major product for sterically hindered bases is the least substituted product (Hofmann). ... |
Why is t-BuOK necessary for this synthesis? |
How would you interpret the IR spectrum of your product if it's peaks match the literature spectrum, but the signals are weak? Could the argument that the sample was very dilute and lots of water was in it work as a viable explanation?
What about in a scenario where the experimental IR spectrum has all necessary pea... |
Could dimerization account for weak IR signals? |
![enter image description here][1]
Did I name it right??
Please help me in naming dispiro compounds
[1]: https://i.stack.imgur.com/8u6jE.png |
Specifically wood and paper and other hydrocarbons, but not necessarily excluding other things that burn. We all know wet wood is very hard to ignite. Wetness here refers to water.
But why is that the case? At the chemical level, **what is it about water that makes it so effective at inhibiting the reaction of hydro... |
Why are wet things harder to ignite than dry things? |
When to use chromatographic separation vs vacuum-assisted rectification distillation? |
Let's look at how you would add in the water and hydroxide ions for the $\ce{MO4^{3-}->MO(OH)}$ reaction.
Step 1: Start with the given metal species, with the metal oxidation states included:
$\ce{M^VO4^{3-}->M^{III}O(OH)}$
Step 2: Add the electrons according to the oxidation states. Here the oxidation stat... |
Let's look at how you would add in the water and hydroxide ions for the $\ce{MO4^{3-}->MO(OH)}$ reaction.
Step 1: Start with the given metal species, with the metal oxidation states included:
$\ce{M^VO4^{3-}->M^{III}O(OH)}$
Step 2: Add the electrons according to the oxidation states. Here the oxidation stat... |
Let's look at how you would add in the water and hydroxide ions for the $\ce{MO4^{3-}->MO(OH)}$ reaction.
Step 1: Start with the given metal species, with the metal oxidation states included:
$\ce{M^VO4^{3-}->M^{III}O(OH)}$
Step 2: Add the electrons according to the oxidation states. Here the oxidation stat... |
> Write the four half cell reactions from the Latimer diagram for a metal $(\ce{M})$ in basic solution.
> $$\ce{\overset{+6}{M}O4^2-(aq) ->[\pu{0.25 V}] \overset{+5}{M}O4^3-(aq) ->[\pu{0.55 V}] \overset{+3}{M}O(OH)(s) ->[\pu{0.42 V}] \overset{+2}{M}(OH)2(s) ->[\pu{-0.89 V}] \overset{0}{M}(s)}$$
I can only come up... |
What substances could be used to gelify 60% hydrogen peroxide? I imagine anything organic like agar would be broken down by the radicals. I tried looking up what dentists use and the only thing that came up was glycerine, which I know from experience doesn't make gels with water, so I doubt it would work with H2O2. |
What substances could be used to gelify 60% hydrogen peroxide? I imagine anything organic like agar would be broken down by the radicals. I tried looking up what dentists use and the only thing that came up was glycerine, which I know from experience doesn't make gels with water, so I doubt it would work with $\ce{H2O2... |
I know about the exceptional stability of [Cyclopropylmethyl carbocation][1].
[1]: https://chemistry.stackexchange.com/q/19090/73527
In some books it is given that cyclo propane and butane carbo cation is highly unstable due to their **high strain**
That is true and quite acceptable
But just like Cyclopropylmet... |
I know about the exceptional stability of [Cyclopropylmethyl carbocation][1].
[1]: https://chemistry.stackexchange.com/q/19090/73527
In some books it is given that cyclo propane and butane carbo cation is highly unstable due to their **high strain**
That is true and quite acceptable
But just like Cyclopropylmet... |
I want to make aspirin. Normal method is to react salicylic acid with acetic anhydride, but it is extremely hard to find acetic anhydride. How may I synthesize aspirin with acetic acid and salicylic acid only?
I have watched a video where someone makes it with sulphuric acid, salicylic acid and acetic acid. Can I us... |
Protic solvents can form a tight shell around a nucleophile. But what's stopping any polar solvent from doing so? Shouldn't a polar solvent surround negatively charged $F^-$ with its partially positive side? |
Why polar aprotic solvents don't decrease nucleophilicity? |
Could someone please explain these specific questions physically (especially the first question!)? I understand the corresponding mathematical proofs, but not the physical reasoning? I have looked online and can only find answers to what I believe correspond with my second question.
- Why is isothermal work larger ... |
I know about the exceptional stability of [Cyclopropylmethyl carbocation][1].
[1]: https://chemistry.stackexchange.com/q/19090/73527
In some books it is given that cyclopropane and cyclobutane carbocation is highly unstable due to their **high strain**.
That is true and quite acceptable, but just like cy... |
What is the order of stability of the cyclobutane and cyclopropane carbocations? |
I know about the exceptional stability of [Cyclopropylmethyl carbocation][1].
[1]: https://chemistry.stackexchange.com/q/19090/73527
In some books it is given that cyclopropyl and cyclobutyl carbocations are highly unstable due to their **high strain**.
That is true and quite acceptable, but just like cyc... |
What is the order of stability of the cyclobutyl and cyclopropyl carbocations? |
is $ FeCO_3 → FeO + CO_2$ correctly balanced? |
According to this link, the temperature of **(1) LPG gas is above 1700 degree Celsius**: https://chemistry.stackexchange.com/questions/26315/what-is-the-temperature-of-heat-generated-from-lpg-gas
Many of us are familiar with pan-frying meat (steak, pan-frying the chicken breast etc).
Next, consider this - when yo... |
If LPG gas burners can reach temperatures above 1700 degree celcious then how do HCA and PAH not develop in extreme amounts during cooking? |
How do you differentiate between the three?
I read that "Spectrometry deals with the measurement of a specific spectrum. There are four primary types of spectrometers:
1. Mass spectrometry 2. Neutron triple axis spectrometry 3. Ion-mobility spectrometry 4. Rutherford backscattering spectrometry"
How about Ram... |
I know about the exceptional stability of [Cyclopropylmethyl carbocation][1].
[1]: https://chemistry.stackexchange.com/q/19090/73527
In some books it is given that cyclopropyl and cyclobutyl carbocations are highly unstable due to their **high strain**.
That is true and quite acceptable, but just like cyc... |
Why polar aprotic solvents don't surround negatively charged nucleophiles? |
Picric acid is stored under a layer of water to prevent an explosion.
What is the right way to measure the amount of Picric acid that taken out? It is wet and containing water. |
Picric acid, how to weight it? |
Picric acid is stored under a layer of water to prevent an explosion.
What is the right way to measure the amount of picric acid that taken out? It is wet and containing water. |
How to weight picric acid? |
I've been stuck on this problem for a while. Could someone walk me through the beginning steps? I should be good to go with some guidance. Would I use Boyle's law in attemp to find the final volume once the partition is removed?[![**enter image description here**][1]][1] Reformatted the photo, my apologies.
... |
Can someone walk me through this gas mixture question? |
I've been stuck on this problem for a while. Could someone walk me through the beginning steps? I should be good to go with some guidance. Would I use Boyle's law in attempt to find the final volume once the partition is removed?[![**enter image description here**][1]][1] Reformatted the photo, my apologies.
... |
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