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Beta sheets are illustrated as such in most diagrams, where:
1. In an antiparallel B sheet, the polypeptide strands are arranged such that a C=O and an NH from adjacent strands face each other, and the H forms... |
Why are hydrogen bonds in an antiparallel beta sheet stronger than those in parallel beta sheets? |
I am modelling H2O2 decomposition in Chemkin Pro and I have difficulty finding Cp (Specific heat at constant pressure) for liquid H2O2 for various temperature ranges.
My ultimate aim is to find the 14 NASA polynomial coefficients so that I can input them in Chemkin Pro. For that I need a range of Cp vs T data, so t... |
Say we've a cubic crystal of unity edge length.
A set of planes in such a crystal is specified by their miller indice as $(3 2 0)$. One of these planes then has intercepts on the axes as $(2 ,3 ,\infty)$.
It's well known that the interplanar distance between two adjacent planes in a cubic lattice is given
$d_{h... |
I'm trying to follow the Krebs cycle step by step, accounting for the number of hydrogens in
each molecule before and after reactions.
I've run into a problem starting from step 3.
[![Citric Acid Cycle - Step 3][1]][1]
[1]: https://i.stack.imgur.com/31ax1.png
Isocitrate has five hydrogens.
It undergo... |
Oxidative degradation by oxygen certainly occurs and has been studied [1], [2]. I can't access the papers. I've seen no mention of UV degradation, but that doesn't mean it does not happen.
[1]: https://ntnuopen.ntnu.no/ntnu-xmlui/bitstream/handle/11250/2461998/Vevelstad_Oxidative+degradation+of+2-ethanolamine.pd... |
Potassium chloride has a greater ionic radius than sodium chloride. How does this affect the fall in rate of increase in conductivity as concentration concentrations? I know the following factors affect the plateauing of the curve:
lesser dissociation, the equilibrium is disturbed as a result of lack of water molec... |
How does the cation radius affect the rate of increase of the electrical conductivity of a salt in aqueous solution? |
Oxidative degradation by oxygen certainly occurs and has been studied [1], [2]. I can't access the papers so I have no information on possible mechanisms. I've seen no mention of UV degradation, but that doesn't mean it does not happen.
[1]: https://ntnuopen.ntnu.no/ntnu-xmlui/bitstream/handle/11250/2461998/Veve... |
The [FFC Cambridge process][1] with platinium electrodes allows the reduction of almost any metal oxide to a pure metal, with an oxygen byproduct.
So far, so good. What I'm trying to understand is how it would handle mixtures of of materials. For example, if it was a mixture of iron oide and titanium oxide, what w... |
Potassium chloride has a greater ionic radius than sodium chloride. How does this affect the fall in rate of increase in conductivity as concentration concentrations? I know the following factors affect the plateauing of the curve:
lesser dissociation, the equilibrium is disturbed as a result of lack of water molec... |
Potassium chloride has a greater ionic radius than sodium chloride. How does this affect the fall in rate of increase in conductivity as concentration concentrations? I know the following factors affect the plateauing of the curve:
lesser dissociation, the equilibrium is disturbed as a result of lack of water molec... |
>[...] we still put it in polar category
If you search for amino acid classification, you will find that there is no agreement on how to classify cysteine.
What you should know is that cysteine has different roles in proteins. In cysteine proteases, it acts as a nucleophile (and its surrounding often makes it mor... |
Cysteine amino acid has an embedded sulfur group in its side chain. Looking at the electronegativity difference of hydrogen and sulfur, it can be considered a non-polar side chain because the electronegativity difference is less than 0.5. This makes it non-polar but still we put it in polar category, why? |
Why is the amino acid cysteine classified as polar? |
I am forming Fmoc-valine-citrulline dipeptide, and below is the literature protocol I am following (from [*Bioconjugate Chem* **2002,** *13* (4), 855-869](https://doi.org/10.1021/bc025536j)):
> ### Formation of Fmoc-Val-Cit
> Fmoc-Val-OSuc (succinimidyl ester) ($\pu{14.91 mmol}$) in DME ($\pu{40 mL}$) was added to ... |
What is the correct electronic configuration of darmstadtium ($Ds$; $Z = 110$)? |
Potassium chloride has a greater ionic radius than sodium chloride. How does this affect the fall in rate of increase in conductivity as concentration concentrations? I know the following factors affect the plateauing of the curve:
lesser dissociation, the equilibrium is disturbed as a result of lack of water molec... |
I was under the impression that the electrical conductivity should increase initially, then begin to plateau, then fall past the saturation point for strong electrolytes. However, from this, I see that the conductivity of magnesium chloride does not follow this ( it is decreasing with increasing concentration) , BUT th... |
Can someone explain why the electrical conductivity of magnesium chloride decreases with increasing concentration? |
Potassium chloride has a greater ionic radius than sodium chloride. How does this affect the fall in rate of increase in conductivity as concentration concentrations? I know the following factors affect the plateauing of the curve:
lesser dissociation, the equilibrium is disturbed as a result of lack of water molec... |
How does the cation radius affect the rate of increase of the electrical conductivity of a salt in aqueous solution? |
I was under the impression that the electrical conductivity should increase initially, then begin to plateau, then fall past the saturation point for strong electrolytes. However, from this, I see that the conductivity of magnesium chloride does not follow this ( it is decreasing with increasing concentration) , BUT th... |
Can someone explain why the electrical conductivity of magnesium chloride decreases with increasing concentration? |
Some of the places, the electronic configuration of darmstadtium ($\ce{Ds}$) is given as $\mathrm{6d^9 7s^1}$ while at some other places, it is $\mathrm{6d^8 7s^2}$. Which among the two is correct?
[![darmstadtium (encyclopedia Britanica][1]][1]
[![darmstadtium (PubChem)][2]][2]
[1]: https://i.stack.imgu... |
What is the correct electronic configuration of darmstadtium? |
It is seems obvious that if you increase the REACTANT ONLY, the position of Equilibrium will move to the product side. Thus making more product if you measured it again in the second equilibrium. HOWEVER, what will happened if you increase BOTH of the product and reactant? |
Can iron oxide dissolved in well point water stored in a 1000l plastic tank be removed by using a 12V battery charger and simple electrodes? If so what material should the electrodes consist of? |
Can iron oxide in well-point water be removed by electrolysis? |
I am trying to use the Induction furnace mechanism (like described via [this video][1]), for heating part of [the Muffle furnace][2], as one [dental porcelain furnace][3] prototype.
So, my plan is to put [copper coil][4] with frequency around 10 ~ 4000 HZ, and placing some iron bar inside the ceramic container (... |
My textbook states that: Henry Moseley found using x-rays that the atomic number of each element has a characteristic positive charge.
I don't know much about x-rays and can't find an answer online or elsewhere. How does this technique work ?
My thoughts are that maybe all protons emit x-ray photons at the same ... |
How can x-rays show how many protons are in a nucleus? |
From this website, I obtained values of bond dissociation energy of C-O and C-F bonds:
http://www.wiredchemist.com/chemistry/data/bond_energies_lengths.html
C-F 485 KJmol-1
C-O 358 KJmol-1
I have read an explanation saying that is because of fluorine being more electronegative than Oxygen, consequent... |
Why is C—F bond stronger than C—O? |
From [this website](http://www.wiredchemist.com/chemistry/data/bond_energies_lengths.html), I obtained values of bond dissociation energy of C-O and C-F bonds:
C-F 485 KJmol-1
C-O 358 KJmol-1
I have read an explanation saying that is because of fluorine being more electronegative than oxygen, consequently... |
From [this website](http://www.wiredchemist.com/chemistry/data/bond_energies_lengths.html), I obtained values of bond dissociation energy of C-O and C-F bonds:
C-F 485 KJmol-1
C-O 358 KJmol-1
I have read an explanation saying that is because of fluorine being more electronegative than oxygen, consequently... |
Im having trouble understanding Scatchard plots.
Y Axis = Bound/Free Ligand
X Axis = Bound Ligand
The graph has a negative slope.
**Why when there is almost no Bound (Y axis = 0) do we get a high positive number for Bound ligand on the X Axis corresponding to Receptor concentration? if there is no bound how ... |
I am trying to use the Induction furnace mechanism (like described via [this video][1]), for heating part of [the Muffle furnace][2], as one [dental porcelain furnace][3] prototype.
So, my plan is to put [copper coil][4] with frequency around 10 ~ 4000 HZ, and placing some iron bar inside the ceramic container (... |
I was reading a research article related to winter fog, so the researcher collected aerosols on Whatman 41 filters every 12h, and we know that **Whatman 41 filters** are usually used for **Qualitative analysis** than how come he find out the concentration of Aerosols through **Whatman 41 filter?** I am confused in the ... |
Whatman 41 filter uses for? |
[![enter image description here][1]][1]
The figure shows a unit cell of a hexagonal crystal system. Drawn in bold, is the unit cell. The lightly shaded one is a unit cell as well and has a six fold symmetry along an axis, hence is more symmetrical than the one in bold.
Why then do texts define the unit cell of a ... |
For any lattice a good choice of a unit cell is the one that is the most symmetric.
Now if every lattice made by a body centered tetragonal unit cell can be made by a face centered cubic unit cell ,which is more symmetric ,then why keep the body centered tetragonal unit cell as a class of Bravais lattice ?
[![ente... |
If a good choice of a unit cell should be the one of most symmetry ,then why keep body centered tetragonal if face centered cubic exists? |
Could someone advise me on sources for crystallography and surface sciences? |
In the spectrum of atomic hydrogen, several lines are generally classified together as belonging to a series (for example, Balmer series, Lyman series, Paschen series), What is common to the lines within a series that makes grouping them together logical?
The answers say that each series has a different lower energy... |
I am studying electron collision with molecules, and came across with notation like this $\left(\mathrm{B}^{1} \Sigma_{u}^{+}, \mathrm{c}^{3} \Pi_{u}, \mathrm{a}^{3} \Sigma_{g}^{+}, \mathrm{C}^{1} \Pi_{u}\right)$ for the $H_2$ molecules and I have no idea what they are.
Is there any textbook that explains what this s... |
You can use [GChemPaint][1], which is available on the repositories of many popular distributions. Among its many components for drawing structures, it has a specific tool for Newman's projections.
You can add H, O and many other elements by simply right-clicking on the molecule, and it even allows you to search you... |
I'm currently doing a case study to find out the exact volume of helium gas required for FE tests on ball valves regards to the valves' volume and pressure class and the number of helium tanks needed for it (assuming the test is being done at room temperature)
The specifications of helium gas that is being supplied... |
What is the emf of a galvanic cell? |
The density of a substance depends on its molecular density and packing fraction (where you need to be consistent in definiting the molar volume in calculating both attributes).
However you are looking for a simpler explanation that gets the general trends right. Just looking at molecular mass is too simple—large... |
Let us say there is a container with two ideal gases in it divided by a piston.Volume of ideal below the piston is 2L and above is 8L.Total volume of container is 10L.
n of both is 1 mole and T is 300 for both.
Find the Temp when the ratio between the volume of gases is 4L and 6L.
How I solved it :
$\frac{R*1*300}{2L... |
Let us say there is a container with two ideal gases in it divided by a piston.Volume of ideal below the piston is 2L and above is 8L.Total volume of container is 10L.
n of both is 1 mole and T is 300 for both.
Find the Temp when the ratio between the volume of gases is 4L and 6L.
How I solved it :
$\frac{R*1*300}{2L... |
You asked for assistance getting information about “permanganate based ionic liquid” that can be used at room temperatures. The following two articles may qualify as “permanganate based ionic liquid.” Unfortunately, I do not have access to the full text of these articles so I do not know which ionic liquids are being... |
[Here][1] it writes that nitrohydrochloric acid (possibly Aqua Regia) is of the ratio of $18:82$, which is $1:4.56$ in a simpler form. On Wikipedia and every other source i found the ratio $1:3$. So what's the truth behind this?
Also is Aqua Regis a valid way to call the mixture? On [Wiktionary][2] it says that this... |
Is $18:82$ a valid ratio for Aqua Regia/(s)(nitrohydrochloric acid)? Source below |
According to Hume-Rothery rules: -
*for a solid solution, the atomic sizes of the the solute and solvent must not differ by more than 15%*
Why should it be so? |
I am looking for a silicone based polymer (think PDMS but I need to do some chemical reactions with it) where I can attach on one side (or both, I am not sure yet) another molecule that has a carboxylic acid at the end or an amine. Maybe some of you know of a PDMS derivative that's functionalised at the end?
Many th... |
Silicone based polymer that can be functionalised on one end? |
In $\ce{NaCl}$ electrolysis, on the positive electrode (aka. on the electrode where oxidation happens), $\ce{Cl-}$ ions are oxidized to $\ce{Cl2}$. But why don't we see any $\ce{O^2-}$ (naturally present in water's $\ce{OH-}$ ions) oxidized to $\ce{O^2}$ at all?
**My pre-existing knowledge, may or may not be correc... |
Amides require much harsher conditions to hydrolyse than its ester homologue. An explanation given is that the orbitals holding the lone pair on the nitrogen overlaps with the C=O pi bond to give conjugation, thus introduing a "partial" pi bond between nitrogen and the carbonyl carbon. Consequently, this makes the bond... |
Why do amides require much harsher conditions for hydrolysis than esters? |
Amides require much harsher conditions to hydrolyse than its ester homologue. An explanation given is that the orbitals holding the lone pair on the nitrogen overlaps with the C=O π-bond to give conjugation, thus introducing a "partial" π-bond between nitrogen and the carbonyl carbon. Consequently, this makes the bond ... |
According to the [Hume-Rothery rules](https://en.wikipedia.org/wiki/Hume-Rothery_rules) for the substitutional solid solutions the atomic sizes of the the solute and solvent must not differ by more than 15%.
Why should it be so? |
I am referencing this article: https://en.wikipedia.org/wiki/Rotational_temperature
So, I see that $\theta _R = \frac{(h/2\pi)^2}{2Ik_b}$.
I took the value of $I$ from https://cccbdb.nist.gov/mieigen2x.asp.
However, when I do the calculations for $\theta _R$ by plugging in the numbers, I get
$$\theta _R = ... |
Is there an error on Wikipedia's page on characteristic rotational temperature of HF? |
Let's deem, we have a liquid metal that is multicomponent, for example, type A, B, and C. Is it possible that we single out the type A and put them in a specific shape, for example, a circle?
Let me clarify it, I have a liquid metal, having three different elements, and I poured it in a square framework. I want to s... |
How does steam prevent oxidation in tea leaves? |
Is 18:82 a valid ratio for Aqua Regia/(s)(nitrohydrochloric acid)? Source below |
[Purine](https://en.wikipedia.org/wiki/Purine) is a remarkable substance, given nature choose it as scaffold for two nuclear bases from [DNA/RNA](https://en.wikipedia.org/wiki/Nucleic_acid): [Adenine (A)](https://en.wikipedia.org/wiki/Adenine) and [Guanine (G)](https://en.wikipedia.org/wiki/Guanine). Its structure also... |
What's special about Purine? |
[Purine](https://en.wikipedia.org/wiki/Purine) is a remarkable substance, given nature choose it as scaffold for two nuclear bases from [DNA/RNA](https://en.wikipedia.org/wiki/Nucleic_acid): [Adenine (A)](https://en.wikipedia.org/wiki/Adenine) and [Guanine (G)](https://en.wikipedia.org/wiki/Guanine). Its structure also... |
You asked for assistance getting information about “permanganate based ionic liquid” that can be used at room temperatures. The following two articles(1,2) may qualify as “permanganate based ionic liquid” Unfortunately, I do not have access to the full text of these articles so I do not know which ionic liquids are be... |
I have seen it said that the precise mechanism of action of migraine medicine Topiramate is not known. But I certainly see a resemblance between that molecule and PLP (Pyridoxal phosphate, the activated form of vitamin B6).
[![The molecular structure of topiramate][1]][1]
A significant similarity is that both ha... |
Does migraine medicine Topiramate work by supplanting Pyridoxal phosphate in enzymes? |
My book gives the following reaction:
$$\ce{SiCl4 + H2O -> HCl + Si(OH)4}$$
Since equilibrium favours the formation of weaker acids. How is this reaction able to proceed if a strong acid like HCl is being formed? Am I missing some point here? Or is my interpretation or equilibrium in this case is faulty? |
How is silicic acid formed? |
[![enter image description here][1]][1]
[1]: https://i.stack.imgur.com/9iXXN.png
I was wondering how I could tackle this question? Thank you in advance :) |
I'm currently learning about orbital hybridization in Carbon.
I see that Carbon has an electron configuration of $1s^2$ $2s^2$ $2p^2$
However, there are actually three $p$-orbitals in the second shell, namely $p_x$, $p_y$ and $p_z$ whch could each hold two electrons. However, there are only two electrons to be di... |
So this rule is known about hybridization that:
if 4 groups (atoms/pairs of electrons) are attached to the atom -> sp3
if 3 -> sp2
if 2 -> sp
but isn't that true only to specific elements only like carbon/oxygen/nitrogen..?
If you take CCl4, C is sp3, but chlorine has 4 groups around it but it's still not sp3 ... |
Does this general hybridization rule really apply? |
I'm currently learning about orbital hybridization in Carbon.
I see that Carbon has an electron configuration of $1s^2$ $2s^2$ $2p^2$
However, there are actually three $p$-orbitals in the second shell, namely $p_x$, $p_y$ and $p_z$ whch could each hold two electrons. However, there are only two electrons to be di... |
I'm looking at EPR of a paramagnetic organic molecule in solution that has a very stable free-radical signature with gfactor ~2.0035. All good. Except when watching one particular experiment I saw that the g-factor was drifting [the zero-crossing was slowly moving to the right over the course of 24hrs, i.e. the g-facto... |
Measured g-factor of a free-radical changing as a function of something. But I cant work out what? |
I read that the molecular orbital diagram of cyclobutadiene predicts that it should have a diradical nature as it has two unpaired electrons in two degenerate non bonding orbitals(one in each). Why does this di radical state exist only in cyclobutadiene? Shouldn't other anti aromatic compounds like cyclooctatetraene al... |
Does the process of chemically strengthening glass change its volume? |
How is Cubic Closed Packing "cubic" and also how is hexagonal closed packing "hexagonal"?
I have been thinking over this for a few hours but I am unable to visualise.
[![enter image description here][1]][1]
I understand that when placing the third layer on top of the second layer ,$2$ situations arise:
... |
I read that the molecular orbital diagram of cyclobutadiene predicts that it should have a diradical nature as it has two unpaired electrons in two degenerate non bonding orbitals (one in each).
Why does this diradical state exist only in cyclobutadiene? Shouldn't other anti aromatic compounds, like cyclooctatetraen... |
Does cyclooctatetraene also have a diradical anti-aromatic electronic state? |
In this article [The Kinetics of Hydrogen Atom Recombination][1] they say that in order to form molecular
hydrogen from collision to atom we need a third body to remove the excess energy. That is we have the reaction $H+H+M\rightarrow H_2+M$
I suppose the reason is because if we have the excess this energy wil... |
Why we need a third body to form hydrogen molecule? |
Anti-aromaticity is often not taught very clearly. Let me start, then, by emphasising that this anti-aromatic diradical state should not be taken as a real thing. It is a *purely hypothetical* state that may arise *if* the molecule adopted the shape of a planar regular polygon (i.e. square for $\ce{C4H4}$, octagon for ... |
During a lecture, my professor told us that the probability to form $H_2$ with mass number 3 could be calculated out of the abundances, $\gamma$, of the atoms the molecule is made of: $^{1}H, ^{2}H$. So,
$$
P[H_2] = P[(^{1}H \cap ^{2}H)\ \cup\ (^{2}H \cap ^{1}H)] = P[^{1}H \cap ^{2}H] + P[^{2}H \cap ^{1}H] - P[(^{1... |
In the article [*Discuss. Faraday Soc.* **1962,** *33,* 205](https://doi.org/10.1039/DF9623300205), the authors say that in order to form molecular
hydrogen from collision to atom we need a third body to remove the excess energy. That is we have the reaction $\ce{H + H + M -> H2 + M}$.
I suppose the reason is becau... |
Why is a third body needed in the recombination of two hydrogen atoms? |
During a lecture, my professor told us that the probability to form $H_2$ with mass number 3 could be calculated out of the abundances, $\gamma$, of the atoms the molecule is made of: $^{1}H, ^{2}H$. So,
$$
P[H_2] = P[(^{1}H \cap ^{2}H)\ \cup\ (^{2}H \cap ^{1}H)] = P[^{1}H \cap ^{2}H] + P[^{2}H \cap ^{1}H] - P[(^{1... |
During a lecture, my professor told us that the probability to form $H_2$ with mass number 3 could be calculated out of the abundances, $\gamma$, of the atoms the molecule is made of: $^{1}H, ^{2}H$. So,
$$
P[H_2] = P[(^{1}H \cap ^{2}H)\ \cup\ (^{2}H \cap ^{1}H)] = P[^{1}H \cap ^{2}H] + P[^{2}H \cap ^{1}H] - P[(^{1... |
I've been reading about how energy is released when new chemical bonds are formed but it's hard to find info on how that typically manifests itself (besides that it's via heat). I read somewhere that the valence electrons will move into lower energy orbits during a bond, but I thought that always created a photon. How... |
As [this video](https://www.youtube.com/watch?v=Xhps2HDpTwI) clearly confirms, the hydrolysis of SiCl4 is highly exothermic from breaking of chlorine bonds. The solution boils and solid insoluble Si(OH)4 is produced.
Also, [per Wikipedia](https://en.wikipedia.org/wiki/Silicon_tetrachloride) on the hydrolysis, to qu... |
From [this wiredchemist.com](http://www.wiredchemist.com/chemistry/data/bond_energies_lengths.html), I obtained values of the bond dissociation energies of the $\ce{C-O}$ and $\ce{C-F}$ bonds:
\begin{align}
D_0(\ce{C-F}) &= \pu{485 KJ mol-1}\\
D_0(\ce{C-O}) &= \pu{358 KJ mol-1}
\end{align}
I have read an ex... |
Why is the carbon fluorine bond stronger than the carbon oxygen bond? |
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