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How is silica gel prepared from sand (after extracting it). How many ways can it be used? Is there a way to make it without an oven? |
This is because the Gibbs free energy also depends on the concentration of the reactants and products. Hence, for a reaction, if the energy change is negative it moves forwards, forming more product, which also changes the concentrations of the species involved. The Gibbs energy change at this new concentration will be... |
Why does capping after coupling improve results during solid phase peptide synthesis (SPPS)?
**The Case:** I have conducted a lab experiment where we coupled three Fmoc-protected amino acids, and did a final capping (acetylate) at the end of the synthesis. However, I was told that one can theoretically cap after ev... |
Why does capping after each coupling in Solid phase peptide synthesis improve the results? |
Per this source, [Chemical Reviews: Transition Metal-Tin Chemistry](https://pubs.acs.org/doi/abs/10.1021/cr00091a002), I surmise that a potential safety issue with Tin stems from its ability to create complexes, which can act in distinctly catalytic roles in organic-based reactions.
In particular, the author discus... |
In a book I am reading, it is said
> In the $\ce{HCl}$ molecule, the shared pair of electrons spend more time nearer the chlorine atom. In the $\ce{HF}$ molecule, the shared electrons spend more time nearer the fluorine atom.
What does "spend more time" mean here? Has this been experimentally validated? If yes, h... |
What does it mean that an electron pair "spends more time" nearer an atom? |
I am currently studying the textbook *Infrared and Raman Spectroscopy* by Larkin. In the first chapter of the textbook, the author presents the following table and accompanying explanation:
> [![enter image description here][1]][1]
> The vibrational spectrum may be divided into typical regions shown in Fig. 1.1. ... |
> Which hydrogen of 3-methylcyclohex-2-en-1-one is the least acidic?
>
> [![3-methylcyclohex-2-en-1-one][1]][1]
**According to me it should be 2**, as on its removal there won't be any resonance stabilization as would happen in the other cases. In addition to that a negative charge residing on a carbon attached ... |
**You are correct. Position 2 is the least acidic.**
Position 3 is not the least acidic hydrogen. It might be the most acidic hydrogen. Position 2 is the least acidic hydrogen of the four marked.
What does position 2 have going for it? Why might it not have been marked as the least acidic? The lone pair that wou... |
I am currently studying the textbook *Infrared and Raman Spectroscopy* by Larkin. In the first chapter of the textbook, the author presents the following table and accompanying explanation:
> [![enter image description here][1]][1]
> The vibrational spectrum may be divided into typical regions shown in Fig. 1.1. ... |
I don't know whether my question is on-topic or off-topic. If it is off-topic, please tell where I should ask.
Warren-Cowely Parameter (WCP) define as :
$WCP_{ij} = 1 - \frac{Z_{ij}}{x_j * Z_i} $
consider a two component solutions, A and B. If $WCP>0$, like neighbors are preferred, If $WCP<0$, unlike neigh... |
I would figure the order would be (in order of smallest Rf to largest) W, Z, Y, X. Is the carboxylic acid more polar than the acetic anhydride?
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/wmBdb.png |
What order would these compounds elute in a 3:1 hexanes:ethyl acetate TLC run? |
Making predictions about elution order is always guesswork but based on my experience I would expect acetic acid to streak off the baseline, The benzyl alcohol to be of low Rf but above the acetic acid, the benzyl acetate Y to run high and I really don't know about the acetic anhydride, I suspect it will hydrolyse on t... |
The structure of $\ce{H2CrO4}$ is as follows:
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/3ypbum.jpg
Shell configuration of chromium is 2,8,13,1 i.e. it has only 1 valence electron and only valence electron participate in bonding but Chromium in the above structure is formi... |
The Warren-Cowely Parameter (WCP) for short range solution order is defined as:
$$\mathrm{WCP}_{ij} = 1 - \frac{Z_{ij}}{x_j \cdot Z_i}$$
Consider a two component solution of $\ce{A}$ and $\ce{B}$. If $\mathrm{WCP}>0$, like neighbors are preferred, If $\mathrm{WCP}<0$, unlike neighbors are preferred.
I... |
Given an unsymmetrical alkene in a simple non-stereoselective catalytic hydrogenation reaction. If one would want to investigate the nuances in the catalytic cycle of a dihydride complex leading to the alkane, there are two important transition-states that have to be considered.
1. Insertion of the alkene into one ... |
The Warren-Cowely Parameter (WCP) for short range solution order is defined as:
$$\mathrm{WCP}_{ij} = 1 - \frac{Z_{ij}}{x_j \cdot Z_i}$$
where $Z_{ij}$ is the **partial** Coordination Number (CN) of j atoms around i, $Z_{i}$ is the **total** CN around i, and $ x_{j}$ is the nominal composition of j.
Cons... |
I am working with Morse interatomic potential, I searched through the Internet but I could not find any Morse parameters for Zirconium element. Is there any table, handbook or something like these which list these parameters? or Is it possible to calculate these parameters for hcp metal elements? |
On the question: 'What does "spend more time" mean here?', from a theoretical vantage, why explore approximations that are based on the time-independent Schrödinger equation?
Perhaps instead, this could be viewed as an application of the nonrelativistic version of the Schrödinger equation for the wave function in po... |
I was reading up on the derivation of the values of various critical state functions( $\ce{Vc}$, $\ce{pc}$ and $\ce{Tc}$) from the Van der Waals equation (Physical Chemistry by G.W. Castellan). There, he was about to express a and b in terms of these critical state functions, when I came across this line:
>Since exper... |
Why is it experimentally difficult to accurately find the critical volume of a real gas? |
I am clearly missing something obvious here. I get the Ksp from the CRC for CuI as 1 x10 ^-12.
So, CuI-> Cu+ + I-
So the kinetics ought to be
Ksp=[Cu+][I-]=[s][s]= s^2
Doing the square root and all gives me a solubility of 2.1 mg/L. Hooray, except that everywhere I look, if the solubility is listed at all, it l... |
I was reading up on the derivation of the values of various critical state functions( $\ce{Vc}$, $\ce{pc}$ and $\ce{Tc}$) from the Van der Waals equation (Physical Chemistry by G.W. Castellan). There, he was about to express a and b in terms of these critical state functions, when I came across this line:
>Since exper... |
I am clearly missing something obvious here. I get the $\mathrm{K_{sp}}$ from the CRC for $\ce{CuI}$ as $1\cdot10^{-12}$.
So, $\ce{CuI-> Cu+ + I-}$
So the formula ought to be
$$\mathrm{K_{sp}} = \ce{[Cu+][I-]} =[s][s]= s^2$$
Doing the square root and all gives me a solubility of 2.1 mg/L. Hooray, except... |
Why are these compounds classified as metamers? |
For the longest time, weak acid-strong base titration curves completely baffled me. I understood that the equivalence point of a strong acid-strong base titration is reached when equal numbers of moles of base titrant are added as there are acid analyte, but I didn't realize why the same is true for a weak acid-strong... |
Why does a strong base completely neutralize a weak acid? |
On the question: 'What does "spend more time" mean here?', from a theoretical vantage, why explore approximations that are based on the time-independent Schrödinger equation?
Perhaps instead, this could be viewed as an application of the nonrelativistic version of the time-dependent Schrödinger equation for the wave... |
On the question: 'What does "spend more time" mean here?', from a theoretical vantage, why explore approximations that are based on the time-independent Schrödinger equation?
Perhaps instead, this could be viewed as an application of the nonrelativistic version of the time-dependent Schrödinger equation for the wave... |
When I reacted copper chloride and aluminum foil instead of getting the brown color I got green color. Can anyone share their procedure where the experiment actually succeeded? |
Alternatively, cast your own sheet (or straight your close-to-final piece) using a mold from a chemical resistant 2 part epoxy. Usually, <a href="https://en.wikipedia.org/wiki/Epoxy#Amines">difunctional or polyfunctional amine hardeners</a> confer chemical/temperature resistance, causing a polymerization in a 3D cross-... |
At what temperature does a polyester release toxic gases? |
On the question: 'What does "spend more time" mean here?', from a theoretical vantage, why explore approximations that are based on the time-independent Schrödinger equation?
Perhaps instead, this could be viewed as an application of the nonrelativistic version of the time-dependent Schrödinger equation for the wave... |
On the question: 'What does "spend more time" mean here?', from a theoretical vantage, why explore approximations that are based on the time-independent Schrödinger equation?
Perhaps instead, this could be viewed as an application of the nonrelativistic version of the time-dependent Schrödinger equation for the wave... |
What is the IUPAC name of $\ce{[Cr(H2O)5Cl]Cl2.H2O}$?
The net says that the correct name is Pentaaquachloridochromium(III) chloride.
But do we not have to account for the water molecule present outside the coordination sphere?
|
What’s the qualitative explanation behind the fact that an isothermal increase in surrounding pressure raises the vapor pressure of a liquid? The quantitative expression relating surrounding pressure and fugacity is well-known, but I’d like a qualitative one. |
Why does raising the surrounding pressure raise the vapor pressure of a liquid? |
Boiling point of ammonia is $-33.35\ \mathrm{^{\circ}C}$ and its critical temperature $132.4\ \mathrm{^{\circ}C}$ is well above the room temperature. So we can liquify the ammonia gas by compressing it into a bottle, and store it at room temperature for ever.
(Even though the bottle is kept at room temperature, the... |
Does the temperature of liquid ammonia stored at high pressure, room temperature suddenly drop to −33.35 °C when poured into a bowl? |
I am trying to measure the sugar content in mango pulp (used for food processing).
Using a hydrometer to measure specific gravity is not adequate because the pulp thickness prevent the hydrometer from adjusting its level as expected. As a work around I am diluting the pulp to a 1:1 ratio of water and mesure the gravi... |
Can a refractometer adequately measure sugar content in fruit pulp? |
I am clearly missing something obvious here. I get the $\mathrm{K_{sp}}$ from the CRC for $\ce{CuI}$ as $1.27\cdot10^{-12}$.
So, $\ce{CuI-> Cu+ + I-}$
So the formula ought to be
$$\mathrm{K_{sp}} = \ce{[Cu+][I-]} =[s][s]= s^2$$
Doing the square root and all gives me a solubility of 2.1 mg/L. Hooray, exc... |
[![enter image description here][1]][1]
This reaction is mentioned as incorrect in my exercise book. Why is this so? My guess was that the Magnesium, instead of forming a grignard reagent with the compound and bromine, would instead form a complex with the N atom. However, wouldn't the complex formed be quite unstab... |
Why is this grignard synthesis incorrect? |
My textbook, Atkins' Physical Chemistry, 11th edition, by Atkins, de Paula, and Keeler, says the following:
> The resulting expression
> $$pV = nRT \tag{1A.4}$$
> is the **perfect gas law** (or *perfect gas equation of state*). It is the approximate equation of state of any gas, and becomes increasingly exact... |
My textbook, Atkins' Physical Chemistry, 11th edition, by Atkins, de Paula, and Keeler, says the following:
> The resulting expression
> $$pV = nRT \tag{1A.4}$$
> is the **perfect gas law** (or *perfect gas equation of state*). It is the approximate equation of state of any gas, and becomes increasingly exact... |
> Which of the following compounds should have the longest carbon-carbon double bond?
>
1. $\ce{CH2=C=CH2}$
2. $\ce{H3C-CH=CH2}$
3. $\ce{(H3C)3-C-CH=CH2}$
4. $\ce{(H3C)2C=CH2}$
I know that single bond > double > triple length-wise, but how do you distinguish between double bonds? |
How to distinguish between carbon-carbon double bond lengths? |
Today, my chemistry teacher gave the following organic conversion as homework: benzene to 1-bromo-3-iodobenzene.
I tried something like:
[![synthesis][1]][1]
I am not sure about it, can someone review my conversion (as I have got an exam tomorrow)?
[1]: https://i.stack.imgur.com/qcWzq.png |
How to convert benzene to 1-bromo-3-iodobenzene? |
How to identify an unknown compound with spectroscopic data? |
The following is the molecule I am confused about.
Earlier in my textbook it gives an example of how to name benzenes with 2 or more hydroxyl groups:
My textbook (Nelson 12 Chemistry) is infamous ... |
My textbook, Atkins' Physical Chemistry, 11th edition, by Atkins, de Paula, and Keeler, says the following:
> The resulting expression
> $$pV = nRT \tag{1A.4}$$
> is the **perfect gas law** (or *perfect gas equation of state*). It is the approximate equation of state of any gas, and becomes increasingly exact... |
So after researching thoroughly on multiple different sources about enthalpy (I'm not talking about the equation but the general concept), many credible sources seem to all contradict themselves.
For instance in a textbook published by Pearson, they define enthalpy as "the total heat content of a system". And other ... |
What is enthalpy? Why do some sources define it as "heat content" of a system? |
It appears that a clean preparation of stannous (or stannic nitrate), other than by the possible direct action of gaseous NO2 on SnO (or SnO2?), as suggested generally [by Wikipedia](https://en.wikipedia.org/wiki/Nitrogen_dioxide) below, is not readily found. To quote:
>Conversion to nitrates
>NO2 is used to gene... |
What is amine inversion, and how does it affect basicity?
For instance, why is $\ce{Et3N}$ less basic than (2.2.2.)cyclohexyl-amine despite the +I from ethyl groups? The answer to the question is option 3.
> [![compounds][1]][1]
> Compare the basic strengths of the compounds given:
>
1. (i) > (ii) > (iii)
2... |
How does amine inversion affect basicity? |
As your textbook notes, the relative energy of atomic orbitals is not fixed as you start ionizing your atom. As you ionize, all orbitals drop in energy. However, higher angular momentum orbitals drop more than lower ones, and specifically in your case, the $\mathrm{3d}$ orbitals drop below the $\mathrm{4s}$ orbitals. S... |
It appears that a clean preparation of stannous (or stannic nitrate), other than by the possible direct action of gaseous NO2 on SnO (or SnO2?), as suggested generally [by Wikipedia](https://en.wikipedia.org/wiki/Nitrogen_dioxide) below, is not readily found. To quote:
>Conversion to nitrates
>NO2 is used to gene... |
**This is a quote from my textbook**:
>The irregular trend in the first ionisation enthalpy of 3d lmetals,can be accounted for by considering that the removal of one electron alters the relative energies of 4s and 3d orbitals. So the unipositive ions have dn configuration with no 4s electrons.There is thus a reorganiz... |
It appears that a clean preparation of stannous (or stannic nitrate), other than by the possible direct action of gaseous NO2 on SnO (or SnO2?), as suggested generally [by Wikipedia](https://en.wikipedia.org/wiki/Nitrogen_dioxide) below, is not readily found. To quote:
>Conversion to nitrates
>NO2 is used to gene... |
It appears that a clean preparation of stannous (or stannic nitrate), other than by the possible direct action of gaseous NO2 on SnO (or SnO2?), as suggested generally [by Wikipedia](https://en.wikipedia.org/wiki/Nitrogen_dioxide) below, is not readily found. To quote:
>Conversion to nitrates
>NO2 is used to gene... |
It appears that a clean preparation of stannous (or stannic nitrate), other than by the possible direct action of gaseous NO2 on SnO (or SnO2?), as suggested generally [by Wikipedia](https://en.wikipedia.org/wiki/Nitrogen_dioxide) below, is not readily found. To quote:
>Conversion to nitrates
>NO2 is used to gene... |
Why is benzoic acid well soluble in benzene (and other unpolar solvents, see e.g. [wikipedia][1]). What causes the hydrogen bonds in the solid to break? Something (i.e. polar and ionic substances) is soluble in water because of the hydration enthalpy with water, but i can see no similar cause for a solubility in benzen... |
Enthalpy is a state function, meaning it is a property of a system, and not a process (like heat or work). It is *defined* as
$$H = U + PV,$$
where $H$ is the enthalpy, $U$ is the internal energy of the system, $P$ is the ambient pressure (assumed to be constant), and $V$ is volume.
Why is it defined in this way? ... |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/JpMwy.png
I don't get how the answer can be 2, I thought it would be 5. Since it's expansion, delta S of system must be > 0. Now since its expansion, work must be < 0. If work is less than 0, q > 0 due to the process being isothermal. So t... |
An ideal gas is undergoing an isothermal expansion against a constant external pressure. Which of the following statements is true? |
Wikipedia says that [Carbon Dioxide cannot be liquid under atmospheric pressure][1].
I thought the phase of an element was related to both pressure and temperature.
If that is so, then should you not be able to set the temperature conditions such that you could have a cup of liquid Carbon Dioxide?
[1]: h... |
Why can't Carbon Dioxide be liquid at 1 atm? |
Per this source, [Chemical Reviews: Transition Metal-Tin Chemistry](https://pubs.acs.org/doi/abs/10.1021/cr00091a002), I surmise that a potential safety issue with Tin stems from its ability to create complexes, which can act in distinctly catalytic roles in organic-based reactions.
In particular, the author discus... |
Per this source, [Chemical Reviews: Transition Metal-Tin Chemistry](https://pubs.acs.org/doi/abs/10.1021/cr00091a002), I surmise that a potential safety issue with Tin stems from its ability to create complexes, which can act in distinctly catalytic roles in organic-based reactions.
In particular, the author discus... |
Is an allylic rearrangement possible in formation of Grignard reagent? Going by the following single electron transfer mechanism, I think it's possible. But, I haven't found any references.
 |
pKa of methane is ~50 and that of ammonia is ~37, thus ammonia is a better acid than methane, which implies methane is a better base than ammonia but I dont see how, methane doesn't have any lone pair of electron, neither it has any $^-$OH. How is it possible? |
Is methane better base than ammonia? |
So I was searching about the difference between redox reactions and Lewis Acid-Base reactions and came across classical example of latter,
NH3 + BH3 → NH3BH3
Now in this example what is the oxidation state of borane? Is it +4, if yes then can this example be considered a type of redox reaction also, since boron ... |
What is the oxidation state of Boron in Ammonia Borane? |
> An ideal gas is undergoing an isothermal expansion against a constant external pressure. Which of the following statements is true?
> 1) This process is reversible.
>**2) This process is irreversible.**
> 3) This process is exothermic.
> 4) The system pressure is always in equilibrium with the external p... |
> Are there any solids with hydronium ion in its crystal structure? If so, what are they?
There are crystal structures of acid monohydrates where the acid is deprotonated and the crystal water is protonated, i.e. the hydronium salt has formed. In addition to the hydronium perchlorate (DOI: 10.1107/s0108270103010461)... |
> Is the compound in the picture chiral or achiral?
>
> [![(2E)-3-(3-bromo-2,4,6-trimethylphenyl)-3-chloro-2-methylprop-2-enoic acid][1]][1]
I think it should be achiral for the following reasons:
- There is free rotation. I know, but for every configuration produced by free rotation there is an exactly oppo... |
Are alkenes with bulky groups attached (like the one shown in the picture) chiral or achiral? |
>What is the mechanism for this reaction-
[![enter image description here][1]][1]
My working so far:
[![enter image description here][2]][2]
But my final product doesn't match with the one given. Where did I go wrong (if at all)? How should I have proceeded?
[1]: https://i.stack.imgur.com/hQoBE.jpg
[... |
>What is the mechanism for this reaction-
[![reaction of ethyl (2Z)-but-2-enoate and ethyl 2-sulfanylacetate in the presence of ethoxide ion][1]][1]
My working so far:
[![OP's mechanism][2]][2]
But my final product doesn't match with the one given. Where did I go wrong (if at all)? How should I have proceede... |
> Are there any solids with hydronium ion in its crystal structure? If so, what are they?
There are crystal structures of acid monohydrates where the acid is deprotonated and the crystal water is protonated, i.e. the hydronium salt has formed. In addition to the hydronium perchlorate (DOI: 10.1107/s0108270103010461)... |
> Are there any solids with hydronium ion in its crystal structure? If so, what are they?
There are crystal structures of acid monohydrates where the acid is deprotonated and the crystal water is protonated, i.e. the hydronium salt has formed. In addition to the hydronium perchlorate (DOI: 10.1107/s0108270103010461)... |
Are there other materials that like clay, are plastic but set to form a hard ceramic, especially ones harder than the fired clay? |
Are there plastic materials that turn into ceramics? |
Are there other materials that like clay, are plastic (as in they can be shaped by hand) but set to form a hard ceramic, especially ones harder than the fired clay? |
As to the question does gaseous NH3 directly react with metals, other than complex formations, a more accurate short answer is likely no. A better answer is a reaction may proceed from heat (or other energy sources, like light) induced breakdown products of ammonia interacting with the metal.
A review of the literat... |
$\mathrm{p}K_\mathrm{a}$ of methane is $\sim 50$ and that of ammonia is $\sim 37,$ thus ammonia is a better acid than methane, which implies methane is a better base than ammonia.
But I don't see how: methane doesn't have any lone pair of electron, neither it has any $\ce{OH-}.$ How is it possible? |
Per this source, [Chemical Reviews: Transition Metal-Tin Chemistry](https://pubs.acs.org/doi/abs/10.1021/cr00091a002), I surmise that a potential safety issue with Tin stems from its ability to create complexes, which can act in distinctly catalytic roles in organic-based reactions.
In particular, the author discus... |
If you know the trends for $1^\text{st}$ ionization energies, a good first approximation for the trends of $n^\text{th}$ ionization energies at any given point is the $1^\text{st}$ ionization trend $n$ elements earlier.
As an example, look at the first and second ionization energies for the second row elements ([Ta... |
If the force constant of iodine in the first excited state is $k=41.78$ N/m and in the ground state it is $170$N/m. What causes this difference?
I know that the formula for calculating k is:
$$ k= (\frac{ΔE_{vib} *2π}{h})^2 µ$$
so is it that the energy difference for the ground state is greater then that of th... |
The force constant of iodine in the first excited state is $k=41.78$ N/m, and in the ground state it is $170$ N/m.
I know that the formula for calculating $k$ is:
$$ k= (\frac{ΔE_{vib} *2π}{h})^2 µ$$
What causes this difference?
Is it that the energy difference for the ground state is greater then that of t... |
You got it wrong. Acidic and basic strength of a compound are **unrelated**, about as much so as the man's name and his weight. Within the definition you and I are currently using ([Brønsted–Lowry][1]), acidity is about having a proton on a polar bond ready to ionize, while basicity is about having electron pairs ready... |
I had a chemistry lab where we had to titrate three solutions with $\ce{HCl}$: a buffer, a diluted buffer and deionized water. My partner and I didn't label the charts we made, so now I have to figure out which one is which.
The way I see is that from the Henderson-Hasselbalch equation:
$\mathrm{p}\ce{H} = \mathrm... |
Strength of weak acids and bases: Is methane better base than ammonia? |
As to the question does gaseous NH3 directly react with metals, other than complex formations, a more accurate short answer is likely no. A better answer is a reaction may proceed from heat (or other energy sources, like light) induced breakdown products of ammonia interacting with the metal.
A review of the literat... |
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