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I've worked this problem and seem to be off by a factor of $2$ somehow. From Callister, $6$th edition, problem $3.56W$ (but I don't have access to the "W" web material that actually explains Bragg diffraction). Using other texts, I found that plane spacing $d$ satisfies
$$\frac{1}{d^2} = \frac{h^2}{a^2} + \frac{k^2... |
I've worked this problem and seem to be off by a factor of $2$ somehow. From Callister, 6th edition, problem 3.56W (but I don't have access to the "W" web material that actually explains Bragg diffraction). Using other texts, I found that plane spacing $d$ satisfies
$$\frac{1}{d^2} = \frac{h^2}{a^2} + \frac{k^2}{b^... |
I am using cystamine (free based) to conjugate to a phosphate group on an oligonucleotide. I tried several keyword searches on Google for neutralizing the dihydrochloride at the ends of the cystamine. But, I am unable to find a protocol. I had once found a procedure for the process, but I did not reference it and hence... |
How can I free base cystamine dihydrochloride? |
I'm interested in DIY photo development and I came across a reversal process that uses chemicals easily available at the grocery store. The purpose of a reversal process is to take a partially developed negative, which is a suspension of Silver & Silver Bromide in gelatin, and turn it into a positive by removing the Si... |
Hydrogen Peroxide & Vinegar Film reversal, can someone help me understand this reaction? |
Phys.org's [Giant lasers crystallize water with shockwaves, revealing the atomic structure of superionic ice](https://phys.org/news/2019-05-giant-lasers-crystallize-shockwaves-revealing.html) links to
- Nature Physics: [Experimental evidence for superionic water ice using shock compression](https://www.nature.com/... |
### Background (hydrogen)
In the case of recently liquified hydrogen (which is quite cold of course) it must be re-equilibrated before loading on to a rocket as fuel to avoid a sudden exothermic equilibration of the ratio of the *ortho-* and *para-* forms. This is because the nuclear spin degree of freedom (singlet ... |
How to find the number of valence electrons with the help of quantum numbers? |
*All* fields of science (biology, chemistry, physics, and geology) use *both* natural and base-10 logarithms.
Is there a distinguishing characteristic that (typically) determines when one is used vs. the other? Yes: *There is a class of applications where the natural log is used, and a qualtitatively different clas... |
Why is it technically inaccurate to say that the decrease in reactivity of halogens is due to decreasing electronegativity? |
From Atkins' Physical Chemistry,
>The electronegativity is a parameter introduced by Linus Pauling as a measure of the
power of an atom to attract electrons to itself when it is part of a compound. Pauling used valence-bond arguments to suggest that an appropriate numerical scale of electronegativities could be de... |
I'm interested in DIY photo development and I came across a reversal process that uses chemicals easily available at the grocery store. The purpose of a reversal process is to take a partially developed negative, which is a suspension of silver and silver bromide in gelatin, and turn it into a positive by removing the ... |
I know that Raoult's law holds true only for a non volatile solute in a volatile solvent mixture wherein the vapour pressure of the solution gets lowered due to the addition of solute.
1) Now, first of all does it hold for a mixture of immiscible liquids ?
2) Does it hold for a mixture of immiscible liquids under... |
While talking about the gaseous state of matter we came to the topic of London Dispersion Forces caused by the generation of a dipole in one atom which induces a dipole in another. While talking about the cause of such an interaction I stated that, since Schrödinger's equation for multi-electron atoms is time dependent... |
How are London Dispersion Forces generated? |
I'm guessing, of course, but my answer is: graph paper.
Every proportionality produces a plot on cartesian graph paper
that is a straight line. And, every power law produces a plot
on log-log paper that is a straight line. Every exponential
(exponentials are faster-rising than any power law) can be made to de... |
It is often said that lithium follows the duet rule instead of the octet rule, unlike the more "usual" main-group elements.
My question is the following:
Does this hold for $\ce{Be, Na}$ and $\ce{Mg}$ as well? |
I know that Raoult's law holds true only for a non volatile solute in a volatile solvent mixture wherein the vapour pressure of the solution gets lowered due to the addition of solute.
1) Now, first of all does it hold for a mixture of immiscible liquids ?
2) Does it hold for a mixture of immiscible liquids under... |
Does Raoult's law hold for immiscible liquids? |
I need to get help with a question regarding hydrogen permeation which I do not really how to get around.
The statement is as following:
A steel container contains helium gas at high pressure (100 bara). Surrounding it is hydrogen gas at a lower pressure (approx. 3 bara) and at a great volume. Hydrogen can permeate... |
Hydrogen permeation from low to high absolute pressure area due to difference in partial pressure? |
I need to get help with a question regarding hydrogen permeation which I do not really how to get around.
The statement is as following:
A steel container contains helium gas at high pressure (100 bara). Surrounding it is hydrogen gas at a lower pressure (approx. 3 bara) and at a great volume. Hydrogen can permeate... |
>Now, first of all does it hold for a mixture of immiscible liquids ?
From Wikipedia on [Raoult's law][1],
>it states that the partial pressure of each component of an **ideal mixture** of liquids is equal to the vapor pressure of the pure component multiplied by its mole fraction in the mixture. In consequence, th... |
>[![enter image description here][1]][1]
> Mechanism of Cannizzaro from [wikipedia][2]
I am trying to understand how to rationalize in the first step of third row that the hydrogen act as a leaving group and a nucleophile. After googling, I found this [quora post][3], from which the only notable information I gathe... |
In the mechanism of Cannizzaro reaction, how do we justify hydrogen acting as leaving group? |
>[![enter image description here][1]][1]
> Mechanism of Cannizzaro from [wikipedia][2]
I am trying to understand how to rationalize in the first step of third row that the hydrogen act as a leaving group and a nucleophile. After googling, I found this [quora post][3], from which the only notable information I gathe... |
In the mechanism of Cannizzaro reaction, how do we rationalize hydrogen acting as leaving group? |
I wonder if it is not a problem that there is another -nh2 group in the molecule not connected to aromatic ring and if it can react with HNO2, too, I mean this one connected to sulphur atom. Sorry for not much experience, I'm new here, don't be nasty. Should it be essential not to have such group to have this reaction ... |
Does HNO2 react only with amine group connected to aromatic ring or other amine groups in the compound to create diazonium compound? |
I know that Raoult's law holds true only for a non volatile solute in a volatile solvent mixture wherein the vapour pressure of the solution gets lowered due to the addition of solute.
1) Now, first of all does it hold for a mixture of immiscible liquids ?
2) Does it hold for a mixture of immiscible liquids under... |
Consider the Electrolysis of water reaction
$$H_2O \rightarrow H_2+\frac{1}{2}O_2$$
At room temperature and atmospheric pressure, the change in enthalpy of this reaction is $\Delta H=+286kJ/mol$. Now at constant pressure, $\Delta H=Q +W_{other}$, so in order for this reaction to occur, at the bare minimum, we *must* ... |
I wonder if it is not a problem that there is another $\ce{-NH2}$ group in the molecule not connected to aromatic ring and if it can react with $\ce{HNO2}$ too. I mean the one connected to sulphur atom.
Should it be essential not to have such group to have this reaction nicely going?
[![Diazonization][1]][1]
... |
Is diazonization of an aromatic amine possible if the compounds also contains a sulphonamide? |
Below I have given three graphs for the $\ce{1s}$ orbital.
$R(r)$ is the radial part of the wave function of the electron. $R^2(r)$ is the radial part of the wave function of the electron multiplied by its complex conjugate which gives us the probability of finding the electron at some point. $R^2(r)4πr^{2}dr$ is wh... |
What is the radial probability distribution function and what is it's significance? |
I'm interested in DIY photo development and I came across a reversal process that uses chemicals easily available at the grocery store. The purpose of a reversal process is to take a partially developed negative, which is a suspension of silver and silver bromide in gelatin, and turn it into a positive by removing the ... |
For a piece of coursework I am doing, I need to calculate the atomic packing factor of some ionic compounds. I have had no formal teaching in this area, so what I know comes from information I have found on the internet.
I take that the atomic packing factor is given by:
$$
APF = \frac{V_\text{atoms}}{V_\text{unit... |
What is the difference between combusting and oxidizing? Oxidation of alcohols leads to formation of aldehydes and carboxylic acid whereas the combustion of alcohols leads to the formation of carbon dioxide and water. What is going on if oxygen is reacting with the same molecule? |
Below I have given three graphs for the $\ce{1s}$ orbital.
$R(r)$ is the radial part of the wave function of the electron. $R^2(r)$ is the radial part of the wave function of the electron multiplied by its complex conjugate which gives us the probability of finding the electron at some point. $R^2(r)4πr^{2}dr$ is wh... |
For a piece of coursework I am doing, I need to calculate the atomic packing factor of some ionic compounds. I have had no formal teaching in this area, so what I know comes from information I have found on the internet.
I take that the atomic packing factor is given by:
$$
APF = \frac{V_\text{atoms}}{V_\text{unit... |
What is the radial probability distribution function and what is its significance? |
Consider the electrolysis of water reaction:
$$\ce{H_2O -> H_2 + 1/2O_2}$$
At room temperature and atmospheric pressure, the change in enthalpy of this reaction is $\Delta H = \pu{+286 kJ mol-1}$. Now at constant pressure, $\Delta H = Q +W_\text{other}$, so in order for this reaction to occur, at the bare minimum, we... |
Consider the electrolysis of water reaction:
$$\ce{H_2O -> H_2 + 1/2O_2}$$
At room temperature and atmospheric pressure, the change in enthalpy of this reaction is $\Delta H = \pu{+286 kJ mol-1}$. Now at constant pressure, $\Delta H = Q + W_\text{other}$, so in order for this reaction to occur, at the bare minimum, w... |
My research team and I are working on a bimetallic alloy consisting of Zinc and Platinum. We have looked for papers regarding the composition of Zinc-Platinum alloy. But there aren't many papers out there.
So far, we have found only one paper:
Moser, Z. The Pt-Zn (Platinum-Zinc) system. *JPE* **1991,** *12* (4), 4... |
It doesn't get harder to add an electron to a halogen atom as you go down the group! It just gets less easy (Ref 1). Big distinction, since the addition of an electron to the radical is exothermic. However, other than this imprecision in the graphic, it is generally true that reactivity drops as you go down the column,... |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/3QIP7.png
Hello, This is a highschool exercise. According to what I took (look for the longest chain, start close to the branches, etc etc) I see two paths I could follow to give me a Hexane.
One where you go through the carbon in the met... |
Would this Hexane have di ethyl and a methyl or an ethyl and an isopropyl? |
The Medium.com article [Mars Phoenix Lander, 10 Years Later](https://medium.com/@tanyaofmars/mars-phoenix-lander-10-years-later-8b90a8609a68) shows several remarkable images and discoveries on Mars by the Mars Phoenix Lander circa 2008.
One image (shown below) shows what looks like droplets of liquid water, condense... |
Although I liked James Gaidis's answer, I do not agree with some of arguments because they are all parts of one or more continuous trends. For instance, look at the melting points and boiling points trends of alkali metals and other trends as illustrated in the following table:
$$
\begin{array}{l|ccc}
\hline
\bf{... |
Although density may be a relatively easily measurable property of solid materials, it may not suggest the most fundamental relationship between mass and volume for the elements. Molar volume (the volume required to contain $6 \times 10^{23}$ atoms of each the elements) is pictured in the graph below (WebElements):
... |
I was solving a question of salt hydrolysis for a mixture of Weak Acid-Base Salts, given the initial amount of salt and Equilibrium constants. I was trying to approach the problem in two ways, Assuming initially that we have all reactants and no products and move the reaction forward OR assuming all the reactants have ... |
Is equilibrium point for a coupled equilibria of arbitary number of coupled reactions is a unique point? |
[![enter image description here][1]][1]
According to what I took (look for the longest chain, start close to the branches, etc etc) I see two paths I could follow to give me a hexane.
One where you go through the carbon in the methyl, and the other by going through two carbons in the ethyl.
In one case I'm left ... |
Is diethyl and methyl preferred over an ethyl and an isopropyl group as substituents when both give the same longest chain? |
I came across the following information in [this](https://www.compoundchem.com/2014/01/06/element-infographics-group-7) post.
[![Halogens][1]][1]
Below the infographic there is a paragraph with a disclaimer:
>As another disclaimer, the reactivity of the halogens decreasing down the group isn’t actually due... |
The bond angle (F-C-F) of $\ce{CHF_3 > CH_2F_2}$ whereas that of (Cl-C-Cl) $\ce{CH_2Cl_2 > CHCl_3}$ why is this the case? Some explanations I read suggest the bents rule but I am not able to understand the idea well. |
The bond angle $\ce{\angle(F-C-F)}$ of $\ce{CHF_3 > CH_2F_2}$ whereas that of $\ce{\angle(Cl-C-Cl)}$ is $\ce{CH_2Cl_2 > CHCl_3}$ why is this the case? Some explanations I read suggest the Bent's rule but I am not able to understand the idea well. |
Why is the bond angle of trifluoromethane higher than that of difluoromethane? |
I have a reference sheet for inorganic analysis which says that the confirmatory test for ferrous ions is as follows:
>Make a solution of the given salt (whose cation is to identified) and add potassium ferrocyanide [ potassium hexacyanidoferrate(II) ] solution to it.
If a dark blue precipitate is formed, then the ... |
Why are Silicates solid while carbon dioxide being a gas? |
Why are Silicates solid while carbon dioxide is a gas? |
I was solving a question of salt hydrolysis for a mixture of Weak Acid-Base Salts, given the initial amount of salt and Equilibrium constants. I was trying to approach the problem in two ways, Assuming initially that we have all reactants and no products and move the reaction forward OR assuming all the reactants have ... |
I came across the following option of a multiple choice question (The options are in the form of assertion and reasoning side-by-side and the incorrectly matched statements are to be marked):
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/TpbPW.png
According to the answer key, this ... |
Does vinyl chloride deactivate the benzene ring? |
Warning: This is just an effort not complete answer. I also request higher members to give answer / put bounty as this question is not having complete answers.
Borazine is planar. But the borazine ring does not form a perfect hexagon. The bond angle is $117.1°$ at the boron atoms and $122.9°$ at the nitrogen atoms, ... |
To derive it, you have to know how an equilibrium depends on concentration and on temperature.
At the freezing point, pure liquid and the solid are at equilibrium. If you lower to concentration of the liquid by adding solute, you disturb the equilibrium. If you lower the temperature by the right amount, you are bac... |
In my textbook, it is written that the expression for depression in freezing point is
$$ΔT_{f}=K_{f}\cdot m$$
where $ΔT_{f}$ is the freezing point depression (defined as positive value), $K_{f}$ is a constant of the solvent, and $m$ is the molality of the solute.
But how did this expression come about? There... |
I have a physics background and I am interested in the applications of quantum mechanics in predicting chemical reactions, and I’m wondering where should I start?
I am particularly interested in the Quantum chemistry of species dissolved in water. How could one compute the time evolution of a chemical system taking ... |
Which temperature would allow a molecule to vaporize at ultra-low vacuum? |
Which temperature would allow a molecule to vaporize at ultra-low pressure? |
In addition to the other answers:
In the old days, log calculations were not simply a click or press on a computer / calculator, but needed to be looked up in paper tables - which in turn took _man-years of manual calculations_ to produce, and therefore were expensive. Why buy another such booklet for _ln_, if you al... |
*All* fields of science (biology, chemistry, physics, and geology) use *both* natural and base-10 logarithms.
Is there a distinguishing characteristic that (typically) determines when one is used vs. the other? Yes: *There is a class of applications where the natural log is used, and a qualtitatively different clas... |
[Here is an image of the phenomena.][1]
I am doing excitation-emission matrices to test for CDOM, and we just got some brand new quarts cuvettes. When I hold them in front of a light, they're totally clear and clean.
I ran a sample, and in addition to the normal diagonal scattering lines, there are some intense h... |
What causes horizontal lines on an excitation-emission matrix in fluorometry? |
I am doing excitation-emission matrices to test for CDOM, and we just got some brand new quarts cuvettes. When I hold them in front of a light, they're totally clear and clean.
I ran a sample, and in addition to the normal diagonal scattering lines, there are some intense horizontal lines in the lower left of the EE... |
I am doing excitation-emission matrices to test for CDOM, and we just got some brand new quarts cuvettes. When I hold them in front of a light, they're totally clear and clean.
I ran a sample, and in addition to the normal diagonal scattering lines, there are some intense horizontal lines in the lower left of the EE... |
As part of a project on decaffeination methods, I'm looking to see how activated carbon filters can selectively adsorb caffeine in tea and coffee solutions, and avoid adsorbing other taste-giving components.
The technique here is water decaffeination, and involves soaking tea leaves/ coffee beans in hot water, and us... |
How to selectively adsorb caffeine on activated carbon filter? |
I wonder if it is not a problem that there is another $\ce{-NH2}$ group in the molecule not connected to aromatic ring and if it can get protonated and react with $\ce{HNO2}$ too, in this case the one sulphonamide group is containing. Is the first reaction below correct?
Should it be essential not to have such group... |
Is sulphonamide group prone to undergo diazotization? |
I come from a physics background (high school chemistry-only), but am reading Koumura *et al.* (2002), a paper about molecular motors. It contains this figure:
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/eeMhl.png
Being an absolute layman when it comes to naming my molecules I'm ... |
Why are these specific compounds labelled trans and cis? |
I come from a physics background (high school chemistry-only), but am reading [Koumura *et al.* (2002)][1], a paper about molecular motors. It contains this figure:
[![enter image description here][2]][2]
Being an absolute layman when it comes to naming my molecules I'm a little confused as to why the left mole... |
I am reading [Koumura *et al.* (2002)][1], a paper about molecular motors. It contains this figure:
[![enter image description here][2]][2]
Being an absolute layman when it comes to naming my molecules I'm a little confused as to why the left molecules are trans, while the right molecules are cis. Which groups ar... |
Why is Sodium Chloride far and away the most abundant salt dissolved in ocean water. Its two constituent ions do have a very high frequency in the crust of the earth but they are far from the most common. Chlorine is (according to [wikipedia][1]) the 21st most abundant element, and [sodium][2] 6th.
I certainly under... |
I am reading [Koumura *et al.* (2002)][1], a paper about molecular motors. It contains this figure:
[![enter image description here][2]][2]
Being an absolute layman when it comes to naming my molecules I'm a little confused as to why the left molecules are trans, while the right molecules are cis. Which groups ar... |
Why is sodium chloride far and away the most abundant salt dissolved in ocean water. Its two constituent ions do have a very high frequency in the crust of the earth but they are far from the most common. Chlorine is (according to [Wikipedia][1]) the 21st most abundant element, and [sodium][2] 6th.
I certainly under... |
I'm doing a chemistry chromatography lab that wants me to recreate anything I want. I decided to measure how far a pigment goes in each color for the same brand, but I'm stuck at the paper part. I heard there's a specific paper I can use, but I'm broke, so would regular paper or coffee filters do the trick as well? |
Can the paper in thin layer chromatography be any type of paper? |
HCQ does show [antiviral properties in vitro][1], but, in vivo (in humans), when taken after an initial dose of 800mg for 4 days at 600 mg/day, it was not found to prevent COVID-19 in high-risk exposure settings. Thus, it didn't stop people from getting SARS-CoV-2 infection followed by onset of symptoms/severity.
... |
I'm doing a chemistry chromatography lab that wants me to recreate anything I want. I decided to measure how far a pigment goes in each color for the same brand, but I'm stuck at the paper part. I heard there's a specific paper I can use, but I'm broke, so would regular paper or coffee filters do the trick as well? Als... |
As per my [textbook][1]:
> **Partition Chromatography:** Partition chromatography is based on continuous differential partiotioning of components of a mixture between stationary and mobile phases. Paper chromatography is a type of partition chromatography. In paper chromatography, a special quality paper known as ch... |
As the title asks, I am curious about why the sample (ie, an extract of plant's chlorophyl transferred onto paper) must not be dipped into the mobile phase (ie, the solvent which goes up the paper)?
My first guess is that it is because the sample would dissolve into the solvent and only a small portion of the sample... |
How to choose a proper chromatography method to separate substrates? |
In ML4 (Metal—4 ligands)model which has a square planar shape and D4h point group, what is the irreducible representation for the 5 kinds of d orbitals in the central metal? |
How do I label stereogenic centers R or S when there are 3 bonds in the plane and 1 bond coming out? |
We all are familiar with the standard state as 1 bar pressure and 273 K.The standard state can be any well defined state. You can define it in any way that is convenient for you. There is no universal definition. We may want to choose different references depending on the calculation we are doing, so we can choose diff... |
>Compare the **nucleophilic strengths** of the following two compounds:
<img src="https://i.stack.imgur.com/QXgcA.png">
According to me it should be the second one, that is, (2*R*,6*R*)-2,6-dimethyltetrahydropyran because the methyl groups would exert +I effect which would increase the electron density on the oxyge... |
We all are familiar with the standard state as 1 bar pressure and 273 K.The standard state can be any well defined state. You can define it in any way that is convenient for you. There is no universal definition. We may want to choose different references depending on the calculation we are doing, so we can choose diff... |
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