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## Electron tunneling
Tunneling refers to elementary particles moving "through" a potential barrier in the absence of sufficient energy to go "over the barrier". This is roughly equivalent to saying that a particle can occupy two locations and traverse between them even though all paths between those locations have ... |
## Electron tunneling
Tunneling refers to elementary particles moving "through" a potential barrier in the absence of sufficient energy to go "over the barrier". This is roughly equivalent to saying that a particle can occupy two locations and traverse between them even though all paths between those locations have ... |
When applying VSEPR, imagine that the various electron pairs occupy "orbitals", in essence volumes shaped like balloons, protruding from the central atom (in this case chlorine). The electrons ("orbitals") repel each other.
Which repulsive interaction is strongest?
One assumes that, placed in equivalent relative... |
I am a mathematician, not a chemist, so my questions are rather combinatorial. I am intrigued by the possibility of the following binary compound:
$$\ce{\overset{-}{N}=\overset{+}{N}=C=\overset{+}{N}=\overset{-}{N}}$$
which ought to be isoelectronic with carbon suboxide, and thus possibly stable. Does this com... |
Does CN4 with the following structure exist? |
I have the following API's
Itraconazole, Ivermectin, Fenofibrate, Pyrvinium Pamoate, Sulfasalazine, Artesunate, All-Trans Retinoic Acid, Doxycycline, Atovaquone, Extremestane, Syrosingopine and Mebendazole
Why is it that API's require excipients?
Are they necessary for the active pharmaceutical ingredien... |
This is a really basic (perhaps trivial) question, but I just want to confirm:
What are the SI symbols for molar mass, molarity, and molality? For molality and molarity, there is a difference, but I’ve found that the symbol is the same for molarity and molar mass, i.e. M (a big m).
Also, what are the meaningful diff... |
Are Group 2 Metal Fluoride salts more soluble than Group 1 Metal fluoride salts in organic solvent? |
Does the chlorination of 4-methylcyclopentene generate two enantiomers or two diastereomers?
[![enter image description here][1]][1]
I think it makes two enantiomers (or one pair of enantiomer) since the starting compound is achiral, but the answer key says it's two diastereomers.
When I tried making the pro... |
Does 1,3-dichloroallene possess a C2 symmetry axis? |
Are group 2 metal fluorides more soluble in organic solvents then group 1 fluorides? |
The likely reason for this is a steric hindrance. The Clemmensen reduction is very vulnerable to hindrance. See the image below: [![enter image description here][1]][1]
There was also another reaction conducted that had a 67% yield for a gamma keto acid with resonance. See the image below:
[![enter image descript... |
Context:
In the process of trying to calibrate a number of hygrometers, with Sensirion MEMS electronic sensors, I came across the method of using wet salt: an airtight container will stabilize at a predictable relative humidity over time, given a particular salt and temperature.
*For a list of salts and their R... |
A $\pu{0.1036 g}$ sample containing only $\ce{BaCl2}$ and $\ce{NaCl}$ is dissolved in $\pu{50 mL}$ of distilled water. Titrating with $\pu{0.07916 M}$ $\ce{AgNO3}$ requires $\pu{19.46 mL}$ to reach the end point. What is the weight percent of $\ce{BaCl2}$ in the sample?
(Molar mass of $\ce{BaCl2} = \pu{208.232 g mol-... |
In the molecular orbital for octahedral metal-ligand complexes, there is an eg orbital and an eg* orbital. When the the d orbitals on the metal split, it will fill up some of the eg* orbitals I believe. However, my question is that won't these orbitals cancel out with the eg orbitals and make fewer bonds? For example, ... |
How does the anti-bonding eg orbital (eg*) affect the bonding of ligands? |
When attacking tertiary alkyl halides, aren't both of them just supposed to follow $\mathrm{S_N2}$ and substitute the leaving group with Hydride ion? Apparently only $\ce{NaBH4}$ does it and $\ce{LiAlH4}$ causes an $\mathrm{E1}$ elimination resulting in an alkene. Why does that happen? $\ce{LiAlH4}$ does secondary and ... |
In phenyl carbanion, one carbon atom has a lone pair on it:
[![Structure of Benzene Anion][1]][1]
[This answer][2] claims that the anion is aromatic, because "the lone pair on the benzene is in the plane of the ring and hence orthogonal to the conjugated $\pi$-system so that it cannot interact with it."
Why i... |
After a cursory internet search, it appears to me that Hydrogen-3 (a part of Tritiated Water) is the heaviest stable* hydrogen isotope. Oxygen-21 is the heaviest isotope of Oxygen with a half-life of seconds, and Oxygen-16, -17, and -18 are the heaviest stable isotopes (again, this is based on an internet search and ma... |
What is the heaviest possible water using oxygen and hydrogen isotopes, and what might it's physical properties be? |
Consider this problem:
> Which is more acidic, $\ce{MeOH}$ or $\ce{MeSH}$?
According to my teacher:
> To determine which is more acidic, figure out which forms the more stable conjugate base. In this case, $\ce{MeS-}$ is more stable than $\ce{MeO-}$. In general stability reduces in the order: $$\ce{RS- > RP- >... |
Why is negatively charge more stable on sulphur than on oxygen? |
Why is negative charge more stable on sulphur than on oxygen? |
Are Group 2 metal fluoride salts less soluble in organic solvents than Group 1 fluorides? |
When applying VSEPR, imagine that the various electron pairs occupy "orbitals", in essence volumes shaped like balloons, protruding from the central atom (in this case chlorine). The electrons ("orbitals") repel each other.
Which repulsive interaction is strongest?
One assumes that, placed in equivalent relative... |
What does Molecular Orbital Theory allow you to predict? |
Why Heating of certain salts like Lead salts produce crackling sound? |
There is more to it than meets the electronegative eye.
Get into the habit of transferring attributes into energy. In this case the relevant energies are the electron affinity of the base money ($\ce{RO}$ vs $\ce{RS}$) versus the bond energy of the moiety to hydrogen. A strong anionic Bronsted-Lowry base will have... |
## How to do this ##
First, I'll address the *how* of this problem. Although the MOL format is limited to 999 atoms in V2000, it [seems like][1] the limit for V3000 is 999999 (for all objects)? See also [this link][2] about the MOLfile format. Anyway, I can use openbabel like :
obabel -ipdb top500H/[1ahoH][3] -... |
I'm researching about the Mpemba effect and I came across an explanation saying that the effect occurs because at higher temperatures, the hydrogen bonds between the water molecules stretch and store energy and when the water starts to cool, the hydrogen bonds go back to normal and release the stored energy on top of t... |
I was reading through a chapter named 'Solid state' in the NCERT Chemistry book.
I learnt about anisotropy of crystalline solids.
And what I understood was, you measure a certain property of that solid in one direction and it could be X while you measure it in the other direction it could be Y.
I then learnt a... |
## How to do this ##
First, I'll address the *how* of this problem. Although the MOL format is limited to 999 atoms in V2000, it [seems like][1] the limit for V3000 is 999999 (for all objects)? See also [this link][2] about the MOLfile format. Anyway, I can use openbabel on [1aho][3] :
obabel -ipdb top500H/1aho... |
We know that iron(II) ions in water have a green colour. Why we cannot draw the spectrum of iron(II) directly in distilled water to measure the absorbance then determine the concentration of iron(II)? We generally use *ortho*-phenanthroline as a complex agent to form a red-orange coloured complex with iron(II), then me... |
I was reading through a chapter named 'Solid state' in the NCERT Chemistry book.
I learnt about anisotropy of crystalline solids.
And what I understood was, you measure a certain property of that solid in one direction and it could be X while you measure it in the other direction it could be Y.
I then learnt a... |
Frankly speaking, you're reading too much into this phenomenon. Have you ever heard the satisfying crackling noise when you burn logs of wood in a bonfire? I'm sure you must've got the answer by now:
**Decrepitation is more of a physical process rather than a chemical process**.
When we write chemical equations, ... |
Is RS- more basic than RO-? |
Why can Na not be used for the Wurtz reaction of compounds having an acidic group like alcohol or carboxylic acid?
|
In the molecular orbital for octahedral metal-ligand complexes, there is an eg orbital and an eg* orbital. When the the d orbitals on the metal split, it will fill up some of the eg* orbitals I believe. However, my question is that won't these orbitals cancel out with the eg orbitals and make fewer bonds? For example, ... |
How do you use Hess's law to find the enthalpy in this case? |
In short, the aim of my experiment is to determine how the concentration of sulphuric acid in solution affects the mass liberated and deposited at copper electrodes, when copper sulphate is electrolysed.
Over all data points, what I observed is that the mass deposited at the cathode was **lower** than the mass liber... |
How would you know when an acid or base is paired with H2O that it will form an OH- ion or a H3O+ ion? I just started the acid and base equilibrium unit, and I'm just confused on what conditions OH- or H3O+ ions form. |
How to know if a reaction forms H3O+ ions or OH- ions? |
short answer: crushed watermelon seeds (urease)
maybe using urease enzyme is cheating?
Regardless: combine urea in solution with urease, get some ammonia with carbamate intermediary, which rapidly decomposes to ammonia and carbon dioxide.
$$\ce{(NH2)2CO + H2O ->[urease] NH3 + H2NCOOH -> 2NH3(gas) + CO2(gas)}$$... |
This question is motivated by a quote from a TV show:
A detective is looking at a small vial (really a glass tube) that supposedly contains poison. Then the detective says:
> As everyone knows, when any poison is put into a vial, it has a convex meniscus. The meniscus in that vial of poison is concave, which prov... |
Can there be an aqueous solution with a convex meniscus? |
Is this molecule chiral?
\ /Br
-
/ \
I'm not sure how to name it. I think
bromo-1,1,2-trimethyethane. |
Is this bromo-hydrocarbon chiral? |
This question is motivated by a quote from a TV show:
A detective is looking at a small vial (really a glass tube) that supposedly contains poison. Then the detective says:
> You don't have to take AP Chem to know that, in a glass container, the meniscus of a liquid containing poison, like baneberry, curves downw... |
Usually textbooks on CI takes the SCF Hartree-Fock orbitals as a starting point. Can one use the configuration interaction method starting directly from the single-particle Slater determinants avoiding the iterative procedure. This question concerns mainly small molecules like the hydrogen molecule. Do I get a high ina... |
I'm working with some hobby-level gas sensors and I've run across a "calibration" system I don't understand. A general description of this kind of gas sensor is described a bit more in [this question][1] and [also here][6]. They have some selectivity between gases, but anything that will react with atomic oxygen at ele... |
So I know water has a pH of 7. If we add 0.1 mol of a strong acid inside 1 liter of water, it WILL fully dissociate into 0.1 mol of A- and 0.1 mol of H+ thus making the pH of the solution 1.
But what if we add 0.1 mol of a weak acid HA, let's say acetic acid, in 1 liter of water? How would I know how much of this ac... |
How to calculate how much weak acid would dissociate in water? |
I'm in need of hydrochloric acid for cleaning parts before electroplating, but I'd rather not deal with the HCl fumes given off by it, as I'd rather keep my workshop contents from rusting.
Given that HCl basically from what I've understood escapes any container it's put in, I had the idea of putting the container i... |
When you do aromatic substitutions, you usually see the major products with one substituent added. However, my question is why can't you add multiple substituents in one reaction? For example, the image below shows nitrobenzene reacting with Br2 and FeBr3 to add Br to the meta position. However, can't the reaction cont... |
Why doesn't aromatic substitution add at multiple positions in one reaction? |
Take group $13$ oxides as an example. The elements in this group are $\ce{B,Al,Ga,In,Tl}$.
Boron oxide $\ce{B2O3}$ is acidic and $\ce{Al2O3}$ and $\ce{GaO3}$ are amphoteric while $\ce{In2O3}$ and $\ce{Tl2O3}$ are basic in nature.
What is the reason for this? |
When you do aromatic substitutions, you usually see the major products with one substituent added. My question is why can't you add multiple substituents in one reaction? For example, the image below shows nitrobenzene reacting with $\ce{Br2}$ and $\ce{FeBr3}$ to add Br to the meta position. Why can't the reaction cont... |
From my knowledge of transition metal complexes, tetrahedral complexes generally have less splitting (compared to octahedral complexes) because they only involve four ligands are they aren't placed directly near any d-orbitals (unlike octahedral complexes). Furthermore, chloride is a weak-field ligand and therefore for... |
Why is tetrachlorocuprate (II) yellow if it is high-spin? |
When you do aromatic substitutions, you usually see the major products with one substituent added. My question is why can't you add multiple substituents in one reaction? For example, the image below shows nitrobenzene reacting with $\ce{Br2}$ and $\ce{FeBr3}$ to add $\ce{Br}$ to the meta position. Why can't the reacti... |
This question requires idea of the Linear Combination of Atomic Orbitals (LCAO). It involves the following equation:
$\psi_n = \sum\limits_{i} c_{ni}\phi_{i} = c_{n1}\phi_{1} + c_{n2}\phi_{2} + ... c_{ni}\phi_{i}$
Here $\psi_n$ represents the wavefunction for the resulting molecular orbital, $\phi_{i}$ represent... |
Is 2-bromo-3-methylbutane chiral?
[![2-bromo-3-methylbutane][1]][1]
[1]: https://i.stack.imgur.com/u5UQc.png |
Is 2-bromo-3-methylbutane chiral? |
The stability works on the following principle:
>More spread out the electron density, more stable is the compound.
As you can see, sp hybridized carbon atom pulls the electron density to a larger extent, thereby, effectively spreading out the charge.
Can you also think of why this is the reverse for cations?
In th... |
Why does hard water have to pass through the cation exchange resin first followed by the anion exchange resin? Why can't it be the other way around? |
How exactly does copper react with hydrogen peroxide, salt and citric acid? |
I came across a problem that asked
> Select which complex is high spin or spin free octahedral complex.
The term 'spin free' sounds like a complex with no unpaired electrons and I know high spin complexes are those which have unpaired electrons. But the question was was single correct and this got me confused.
... |
Does high spin and spin free mean the same thing? |
I have been modelling excited states of some molecules with similar stucture using TD-DFT theory, however, I have encountered an issue that sometimes transition dipole moment does not align with the direction of experimental. For example, for molecule 1 the right direction of a transition dipole moment is with B3LYP fu... |
I have been given 1HNMR, MALDI-ToF-MS and GPC spectra for a laboratory synthesized sample of polycaprolactone.
The number average molecular weight (Mn) obtained from their analysis differed significantly though:
Mn(1HNMR) = 3186,41 g/mol
Mn(MALDI) = 4751,64 g/mol
Mn(GPC) = 6750,81 g/mol
I tried to find... |
One of the sections about retrosynthesis in Warren's book addresses how to access $\gamma$-hydroxy carbonyl compounds like **ZM181**. This is again one of the examples to advice the reader to check the results for plausibility: while epoxides *often may* be a suitable building block, *here*, the intermediate would rea... |
To answer your question, what if we did utilize the method you propose?
Before going into the details, it should be noted that the Ion-Exchange method is used to remove hardness of water at an industrial scale. The principal reason that this method is preferred over any other hardness removal process is that it has ... |
To answer your question, what if we did utilize the method you propose?
Before going into the details, it should be noted that the Ion-Exchange method is used to remove hardness of water at an industrial scale. The principal reason that this method is preferred over any other hardness removal process is that it has ... |
How can I convert cathodic energy efficiency to overall energy efficiency? |
I'm still working on my concepts related to chemical equilibrium. I came across this question:
> 10mL of a weak acid HA is 20%
> dissociated in water. This solution is completely neutralised by 10 mL
> of $10^{-3}$ M of NaOH.
Is [$\ce{HA}$] = $10^{-3}$ M or is [$\ce{H^+}$] =$10^{-3}$?
Why is it wrong to say... |
When applying VSEPR, imagine that the various electron pairs occupy "orbitals", in essence volumes shaped like balloons, protruding from the central atom (in this case chlorine). The electrons ("orbitals") repel each other.
Which repulsive interaction is strongest?
One assumes that, placed in equivalent relative... |
As @Maurice pointed out, the result of a neutralization reaction is not impacted by the dissociation percentage.
> Is [HA] = 10−3 M or is [H+] =10−3?
[HA]=10^-3.
Always remember, neutralization in aqueous medium depends upon the number of equivalents of acid and base;
$$N_1V_1=N_2V_2 $$ Since V1=V2, therefor... |
Is my logic correct in this case ?
Since the formal charge represents the charge the element possess in a covalent compounds, is it right to say that formal charge is the equivalent term for covalent bonds as is oxidation number is to ionic bonds ? |
Is this analogy right? |
How much CO2 in kg is emitted by using 1 cubic meter of LNG? It is used for a dry booth after painting products.
Unfortunately, this is all information I have. Please note the assumptions for answering this question.
|
How many CO2 is emitted (in kg) by using 1 m3 of LNG? |
I tried doing this problem, but I have some questions that are confusing me:
1) Do we assume the KI+AgCl-->KCl+AgI reaction goes to completion?
2) Is the 0.10M KI unnecessary information? If yes, why do we not need it?
3) Should we setup equilibriums?
Overall, I'm just confused.
Disclaimer: This is not... |
Calculate the concentration of I− in a solution obtained by shaking 0.10 M KI with an excess of AgCl(s)? |
As @Maurice pointed out, the result of a neutralization reaction is not impacted by the dissociation percentage.
> Is $\pu{[}\ce{HA}{] = 10^{−3} M}$ or is $\pu{[}\ce{H+}{] = 10^{−3}}$?
$\pu{[}\ce{HA}{] = 10^{-3}}$.
Always remember, neutralization in aqueous medium depends upon the number of equivalents of acid... |
Your analogy isn't correct. As @Ivan pointed out in the comments, oxidation numbers apply to covalent compounds as well as they do to ionic ones.
You calculate oxidation numbers assuming that the more electronegative atom takes up both the electrons in a bond. Formal charge, on the other hand, is determined assuming... |
How to find enthalpy of solvation for gas phase cation using Hess's law? |
I have seen classification of Mg+2 or any other cation or anion for that matter as an acid or a base, but I have never seen an element labelled as an acid or a base. Isn't there a possibility of Mg+2 being the conjugate acid of Mg a base? If not,why so? |
Is any element base or acid? |
I'm having difficulty visualizing the concept of atomic form factor or atomic scattering factor as it has been presented in a chemistry course on X-ray crystallography that I'm taking. At the moment, I visualize it as such:
[![Rough sketch of X-ray atomic form factor for Fe and C][1]][1]
[1]: https://i.stack.... |
Am I visualizing/understanding atomic form factor correctly? |
Furfual (C5H4O2) has been used as a feedstock for synthesis. Furfurylamine (C5H7NO) is made from Furfural.
Given that industrial manufacturing ammonia is matured, how about furfural, ammonia, hydrogen combine to directly synthesize pyridine.
C5H4O2 + NH3 + H2 -> C5H5N + 2H2O
Is it realizable? |
Furfural $(\ce{C5H4O2})$ has been used as a feedstock for synthesis. Furfurylamine $(\ce{C5H7NO})$ is made from furfural.
Given that industrial manufacturing ammonia is matured, how about combining furfural, ammonia and hydrogen to directly synthesize pyridine? Is the following reaction realizable?
$$\ce{C5H4O2 +... |
I am facing a ween problem. I am trying to find out, how would look like the graph for fluroscence of aesculine (intensity of fluoroscence on Y axis and pH on X axis).
I know, that increasing the pH causes a corresponding increase in the maximum fluorescence intensity from 77.74 (units) in the acidic sample to 146.1... |
How ph affects aesculune fluorescence? |
While solving some Coordination Compounds problems, I came across a problem that asked
> Select which complex is high spin or spin free octahedral complex.
The term 'spin free' sounds like a complex with no unpaired electrons and I know high spin complexes are those which have unpaired electrons. But the question... |
Are high spin complexes and spin free complexes the same thing? |
I have a question regarding biological activity of different isotopes of the same elements, notably $\ce{^206Pb}$ and $\ce{^208Pb}$. Lead is known to be toxic, such that it can replace calcium from bones and iron from hemoglobin for example. Would one isotope behave differently than another in such cases?
When it co... |
Is there any known substance that can decrease fertility of a male?
Less specifically what about one time chemical castrations (ignoring a perfect sterilization)?
I heard about them before once but wasn't sure really. |
The beryllium ion, $\ce{Be^{2+}}$, forms the aquo complex $\ce{[Be(H2O)4]^{2+}}$. According to [LibreTexts][1], this complex is acidic in solution: $$\ce{[Be(H2O)4]^{2+} + H2O -> [Be(H2O)3OH]+ + H3O+}$$
It is not clear to me why it should be acidic. I read [here][2] that "the hydrolysis happens because the $\ce{Be−O... |
Why is hydrated beryllium ion acidic? |
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