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1500 questions
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votes
2 answers
Exocyclic vs. endocyclic double bonds in E1 elimination
What will be the major product of this elimination reaction?
The exocyclic product has more substituent groups on the alkene which should make it more stable but I have heard that exocyclic alkenes are less stable than their endocyclic…
bon
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18
votes
2 answers
In Crystal Field Theory what does Δo=10Dq mean?
While studying the Crystal Field Theory I was told $\mathrm{Dq}$ is a unit, related to the unit $\Delta_{\mathrm{O}}$ by the relation $\Delta_{\mathrm{O}} = 10\ \mathrm{Dq}$. But aren't $\Delta_{\mathrm{O}}$ and $\mathrm{Dq}$ variables, not units?…
Charles
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18
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1 answer
Alkylation of conjugated nitriles - regioselectivity
Why does the enolate of the nitrile attack the alkyl chloride from the bond shown in the picture and not from the far end pi bond?
EJC
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18
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3 answers
What are the correct resonance structures of nitrous oxide?
There was a question in one of my exam papers to draw the resonance structures for $\ce{N2O}$.
These are the ones I drew, but they were not awarded marks:
The ones in the marking scheme are as follows:
Can anyone please explain why mine aren't…
lucy G
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18
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1 answer
What is the relation between surface tension and initial molecular harmonic?
Initial harmonic is measured as Hartree/Bohr^2 ( like IHarmonic=n in Gaussian Software ). As I am from physics background I am used to look at features from their dimension point of view:
Actually surface tension is the only physical feature that I…
Aug
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18
votes
1 answer
Why is diborane cleaved symmetrically by trimethylamine but unsymmetrically by ammonia?
I know that soft bases cleave diborane symmetrically but hard ones don't. However, what makes ammonia harder than trimethylamine? And why does hardness/softness affect this?
RobChem
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18
votes
2 answers
Color of chromate and permanganate
I've heard quite a few times that the chromate and permanganate have a $d^3s$ configuration. Also, their colors arise due to a rapid switching of electrons between the oxygen and metal atoms.
I don't really understand the 'rapid switching'…
ManishEarth
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18
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1 answer
Regioselectivity in electrophilic substitution of pyrrole
In the electrophilic aromatic substitution (EAS) of pyrrole, why is the alpha position preferred over the beta position so much?
EJC
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18
votes
3 answers
Why are water droplets shaped like that?
With nothing to do, I stared at the droplets that get condensed on the glass panel of my window.
Upon examination, these droplets appear to be in some sorta pattern. There are big droplets as well as small ones that fill the space between the big…
most venerable sir
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18
votes
2 answers
Why is the specific heat of water high?
How is the specific heat of water so high?
I was reading the hyperphysics article on it but could not understand it properly.
Paul
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18
votes
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Anomalous electronic configuration of platinum
Why is the electronic configuration of platinum
$$\mathrm{[Xe] 4f^{14} 5d^9 6s^1}$$
and not $\mathrm{[Xe] 4f^{14} 5d^{10} 6s^0}$ or
$\mathrm{[Xe] 4f^{14} 5d^8 6s^2}$?
lambda23
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18
votes
4 answers
How to RAISE the melting point of water?
It is common that adding common salt into water will lower its melting point. But, is there any way to RAISE the melting point of water? Does it lower the boiling point of water as well? Why?
Chin Huan
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18
votes
2 answers
What factors are important for quantitative analysis of a proton 1D-NMR spectrum?
Besides elucidating or verifying a chemical structure, NMR can also be used e.g. for quantifying a mixture of different chemicals.
Depending on the quality of the spectrum and the specific substance, integrating the NMR signals for the same…
Mad Scientist
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18
votes
1 answer
Are matrices a good way to do stoichiometry?
I was never taught in school to use matrices to balance my equation in stoichiometry. But I recently started to review my chemistry and, as I have taken linear algebra, I was suddenly struck by the idea this would be a really efficient way to…
Stan Shunpike
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18
votes
2 answers
How do I determine the absolute configuration experimentally?
Let's say I synthesized or isolated a chiral molecule and want to know the absolute configuration (R or S) of that molecule. I could obviously solve the structure by X-Ray crystallography, but that's a lot of work and I might not want to do that or…
Mad Scientist
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