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Is density functional theory an ab initio method?
The following comment by Wildcat made me think about whether density functional theory (DFT) can be considered an ab initio method.
@Martin-マーチン, this is sort of nitpicking, but DFT (where the last "T" comes from "Theory") can be considered as an…
Martin - マーチン
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Effect of drinking ultra-pure water
What would be the effect if someone were to drink ultra-pure water with an electrical resistivity of $18 \, \mathrm{M} \Omega \! \cdot \! \text{cm}$?
Would they immediately die? Would they just need to pee more? Would $\ce{CO2}$ from the air…
user15949
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Pauli exclusion principle and resonance
I've always been a bit uncomfortable with the concept of more than two electrons in a single orbital-like region(probability-wise) which occurs in resonance.
This seems to disobey Pauli's exclusion principle.
Let's take benzene for example. It has…
ManishEarth
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Acidity of substituted phenols
Phenol has a $\mathrm pK_\mathrm a$ approximately equal to $9.9$.
When one studies the acidity of chlorophenols, one notices the following:
First of all, chlorophenols are more acidic than phenol, due the negative inductive effect (−I) of chlorine,…
mannaia
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Why are there two Hydrogen atoms on some periodic tables?
Most periodic tables only feature one Hydrogen atom, on the top of the first group. But some, like the one I was given, also show Hydrogen in the 7th group, to left of Helium.
Why are there two Hydrogen atoms? What's the difference between the two,…
Zolani13
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Does O2 have a color in the gas phase
I have noticed that liquid $\ce{O2}$ (I clarify it as $\ce{O2}$ because oxygen exists in several other forms which have different colors in the liquid state than $\ce{O2}$) has a light blue color to it.
In the solid state it has a light blue color…
Caters
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Why is the bond length of CO+ less than that of CO?
According to molecular orbital theory, the bond order of $\ce{CO}$ is 3. When $\ce{CO+}$ is formed, the bond order decreases to 2.5, and thus the bond length should increase.
However, the bond length of $\ce{CO+}$ is found to be less than $\ce{CO}$.…
Papul
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Explanation for the trends in nucleophilicity—Orbital interactions or electrostatic attraction
The trend of halide nucleophilicity in polar protic solvents is $$\ce{I- > Br- > Cl- > F-}$$
The reasons given by Solomons and Fryhle[1], and by Wade[2] are basically as follows.
Smaller anions are more solvated than bigger ones because of their…
Apoorv Potnis
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Synthesis Golf II: Erythronolide B
A full FAQ post has been written on meta.chem.SE, explaining the premise of synthesis golf and the 'rules'. Please take a look at this if you haven't already.
This round of synthesis golf concerns the Corey synthesis of Erythronolide B (J. Am.…
NotEvans.
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Why does burnt hair smell bad?
When I use hot stuff like hair straightener on my hair, my hair begins to smell bad, which is very different from smell produced from burning other things. So what's the gas produced that is responsible for this smell?
AksaK
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Why is 1-ethylidene-4-methylcyclohexane chiral?
As far as I can tell, there doesn't seem to be a chiral carbon in the compound, 1-ethylidene-4-methylcyclohexane. The C-4 of the cyclohexane ring has two groups with exactly the same connectivity, and the exocyclic double bond can't give rise to…
orthocresol
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Has anyone even taken a picture of a molecule to confirm the geometry predicted by theory?
Have the geometries of molecules been proven, or are we operating strictly on mathematical theory? To put it over-simplistically: has anyone ever taken a picture of a molecule to compare against their math?
Jonathon Anderson
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Melting and boiling point trend in Group II
The following picture shows the melting and boiling point trends down group II elements.
I have added question marks where the variability in data was rather disturbing (over two hundred degrees Celsius), or where the value is simply disputed.…
Linear Christmas
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Why can't Pd/C and H2 reduce both the alkene and carbonyl portions of α,β-unsaturated carbonyls?
Why is it that the major product of the reduction of chalcones the ketone and not the monoalcohol? In other words, Why isn't the major product a benzyl alcohol?
From what I understand, catalytic hydrogenation can be used to reduce carbonyls as well…
Dissenter
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Unusual Friedel–Crafts alkylation with pivaloyl chloride
In class we were told of an anomalous Friedel–Crafts reaction with a tertiary acid chloride — $\ce{(CH3)3CCOCl}$, or pivaloyl chloride. When this reacts with benzene in the presence of $\ce{AlCl3}$, instead of effecting the normal acylation, it…
Charles
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