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1500 questions
19
votes
2 answers
Can molecules diffuse upstream when emptying a cup of tea?
I was drinking some tea, and I randomly decided to pour some into the toilet in an unbroken stream; can particles travel "upstream" quickly enough to reach the mug of tea? How fast can diffusion occur in this system?
What if I pour it into highly…
James
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19
votes
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Does a neutral dimercury molecule exist?
Is a neutral $\ce{Hg2}$ molecule possible, as a gas under extremely low (partial) pressures? What is the enthalpy of formation or similar?
It is my impression that usual mercury vapors are monatomic? I think it is well-known that a dimer ion…
Jeppe Stig Nielsen
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19
votes
1 answer
How can benzaldehyde have a pKa of 14.9?
There are numerous websites out there which claim that the pKa of benzaldehyde – C6H5CHO – is 14.90. (Just do a Google search for benzaldehyde pka to see what I mean.) This doesn't make sense chemically, as there are no protons in benzaldehyde which…
orthocresol
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19
votes
5 answers
What is the chemical structure / hybridization of sulfuric acid?
I was looking at the chemical structure of $\ce{H2SO4}$.
Intuitively, I would have expected this molecule to be square planar in accordance with $p^2d^2$ or $sp^2d$ hybridization, but instead it is shown to be in a tetrahedral geometry consistent…
bobthejoe
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18
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1 answer
The effect of the groups at para position on SN2 reactivity
Compare the SN2 reactivity order for:
The benzyl group stabilises the transition state of SN2 reaction using the π system of the benzene ring for conjugation with the p- orbital of the electrophilic carbon which is electron deficient.…
Archer
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18
votes
3 answers
Why are ethers treated as substituents and not as functional groups in IUPAC nomenclature?
Why are ethers not considered as functional groups in IUPAC nomenclature?
Let us consider the following example:
Image source
The preferred IUPAC name (PIN) for this compound is 2-ethoxy-1,1-dimethylcyclohexane. And we get this by first point of…
MollyCooL
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18
votes
2 answers
What is the "blue spirit" (or "red spirit") in mercury-free thermometers?
I surmise it's some kind of alcohol, but is there a standard chemical used for these?
One of them just exploded in my students' lab! It was the kind with blue fluid in it.
khaverim
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18
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1 answer
Why does LiAlH4 reduce the double bond of cinnamaldehyde, whereas NaBH4 does not?
I read an answer here about why $\ce{LiAlH_4}$ does not reduce conjugated double bonds, and that $\ce{NaBH_4}$ does. But in the case of cinnamaldehyde, $\ce{LiAlH_4}$ reduces the conjugated double bond and $\ce{NaBH_4}$ does not. Why is it…
Siddharth Venu
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18
votes
2 answers
Arrows used in chemical reactions
A point was raised about arrows used in a chemical reaction. I think we can all agree that $\ce{->}$ arrow in the reaction
$$\ce{A + B -> C} \tag{1}$$
means that the reaction goes in one direction. But what of
$$\ce{A + B <-> C} \tag{2}$$
$$\ce{A +…
MaxW
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18
votes
2 answers
Is it possible to speed up radioactive decay?
I’m aware that elements like $\ce{^14C}$ have a known half-life, which means that over a span of roughly $5730$ years, half of the $\ce{^14C}$ atoms decay into $\ce{^14N}$.
Are there any substances known to speed up this process, that applying it…
DonielF
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18
votes
5 answers
Does chemistry change under high voltage?
Do chemical reactions change when you charge the entire reaction vessel plus or minus $\pu{1 MV}$ or more? Is there a name for such chemistry?
I was looking at "electrochemistry" expecting to see a host of information on charged reactions (either…
CoryG
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18
votes
1 answer
Are the canonical orbitals of Hartree-Fock also the natural orbitals?
My question stems from the comments on my answer to After a unitary transformation, is Koopmans' theorem still valid?. There was some confusion relating to differing terminology referring to different, mostly unrelated density matrices. As of now,…
Tyberius
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18
votes
1 answer
Can I eat the lemons after I have used them as a battery?
After completing the lemon battery experiment, can I eat the lemons when I'm done?
More broadly, what will happen to the lemons? What are the chemical reactions, what chemicals might be present/missing after running my lemons as a zinc/copper…
gingerbreadboy
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18
votes
3 answers
What exactly is "B-strain"?
On factors that influence the stability of carbocations, I came across this peculiar one:
Bulky groups attached to the positively charged $C$-atom (of the carbocation), stabilize it by B-strain, which prevents the C-atom for returning to the…
paracetamol
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18
votes
1 answer
Plutonium having more oxidation states than samarium?
Why does plutonium have more oxidation states than samarium?
Electron configuration of Pu: $\ce{[Rn] 5f^6 7s^2}$
Electron configuration of Sm: $\ce{[Xe] 4f^6 6s^2}$
I thought that only the valence electrons affected the oxidation states, so why does…
user2117