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1500 questions
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What is the role of pH in azo coupling reaction of diazonium with phenol and aniline?
Why is it so that azo coupling with phenol needs basic pH (9–10) and with aniline it needs acidic pH (4–5). How does pH participate in the mechanism? I have searched the internet for quite a while nowhere does it explain the actual ‘role’ of the pH.…
Dhruba Banerjee
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34
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Hypervalency and the octet rule
I realize that the octet rule is more a suggestion than a rule, and that it applies mainly to non-transition metal compounds. Still, compounds that don't have an octet, like $\ce{BH3}$, tend to dimerize or disproportionate in order to achieve an…
ron
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34
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How do I extract cyanide from apple seeds?
I'm working on a crime story about cyanide poisoning from apple seeds. I just would like to have an idea of what processes and extraction techniques might be involved in getting cyanide from the seeds. The character is supposed to have access to a…
Chronos
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34
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Proper typography of "NOx"
I am a journal typesetter, and recently I came to a problem that I'm not sure I know to solve. The question is how to properly typeset the "NOx" abbreviation for nitrogen oxides. Which is typographically correct:
$\mathrm{NO}_x$ (because $x$ is a…
yo'
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What's the difference between a nucleophile and a base?
Obviously it depends on the context whether you would call a particular species a nucleophile or a base but are the two terms largely synonymous or is there a difference?
RobChem
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What would be the effect of the addition of an inert gas to a reaction at equilibrium?
Why does a dissociation reaction shift to the right with the addition of an inert gas?
pcforgeek
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When is it true that more nodes equals higher energy?
Consider all the MOs of some isolated molecule. (It could be a single
atom too; I'll use MO to refer to AOs as well.) Number them in
increasing order of the number of nodes (node = surface where the wave
function has zero density). Orbitals with the…
Silvio Levy
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34
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Why isn't 'chemically-strengthened glass' made with potassium carbonate to begin with?
Instead of making potassium-strengthened glass by creating ordinary soda-lime glass first, then replacing the sodium atoms/ions with potassium by putting the glass in a bath/solution of potassium nitrate, why not replace the 'soda' (sodium…
Kurt Hikes
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What is the molecular structure of xenon hexafluoride?
Xenon hexafluoride, $\ce{XeF6}$, can be obtained by reaction of xenon with excess fluorine gas.
What is the gas-phase structure of the molecule?
What experimental evidence is there to support it, and is there any theory which allows for an…
orthocresol
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Flammability (NFPA) - how is it defined?
I was reading up on a wonderful little chemical compound known as chlorine trifluoride ($\ce{ClF3}$). For a primer, check out Dr. Derek Lowe's blog post here: Sand Won't Save You This Time. The title of the post is quite telling; this compound is so…
KeithS
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Where did amino acids get their one-letter codes?
Some amino acids have a one-letter code that's just the first letter of the name of the amino acid. This makes sense and obviously, since there is more than one amino acid that begins with the same letter, other letters had to be used.
But why were…
Melanie Shebel
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33
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2 answers
What is Drago's rule? Does it really exist?
My textbooks states the Drago's rule in inorganic chemistry as follows:
The more electronegative atom prefers the orbital having more $\mathrm{p}$ character, and lone-pairs or less electronegative elements prefer such orbitals, as have more s…
user37316
33
votes
2 answers
What is the exchange interaction?
As the wikipedia article for the exchange interaction so aptly notes, exchange "has no classical analogue."
How wonderful.
Exchange shows up essentially while enforcing the condition that two electrons should not be distinguishable.
That makes sense…
jheindel
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Sp5 hybridization in cyclopropane?
I have never before heard/read about something as a $sp^5$ hybridization. Today, Henry Rzepa's blog post made me aware of the existance of such a bonding system. That made me search a little bit and I found an entry in a german chemistry forum,…
pH13 - Yet another Philipp
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33
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Why is methanol toxic?
There are two points of view for the answer of this question:
The biological view, the only one that I faced during my research, states that since it can trigger perilous conditions like metabolic acidosis, cause a neurologic sequelae, etc.…
M.A.R.
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