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2 answers
Confusion about direction of dipole arrow in alpha-helices and other molecules
I understand that molecular dipoles are electric dipoles. And electric dipole moment vectors point from the negative to the positive charge.
In class we learned to draw these special molecular dipole arrows (with a "plus" at the beginning) that…
Reto Höhener
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28
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Which compound reacts faster in the Cannizzaro Reaction?
Which reacts faster in the Cannizzaro Reaction?
a) $\ce{OHC-C6H4-NO2}$
b) $\ce{OHC-C6H4-OCH3}$
Obviously, a better hydride releasing group will react faster. Therefore my answer was b, as $\ce{-OCH3}$ shows -I (inductive) effect as well as +R…
Shubham
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Why do cyclic hydrocarbons have higher boiling points than their acyclic isomers?
As pointed out in the comments to this question, cyclic hydrocarbons have higher boiling points than their acyclic isomers. The major attractive force for hydrocarbons should be the London forces, which scale with surface area. My intuition has me…
Ben Norris
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28
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What is Y-aromaticity? Is the trinitromethanide anion aromatic?
The wikipedia article on trinitromethane claims that:
There is some evidence that the anion (which obeys the $4n+2$ Hückel rule) is aromatic.
Unfortunately the citation is behind a paywall so I can't read it but my first obvious question is how…
bon
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28
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How come uranium's relative atomic mass is 238.03 when it only contains isotopes with a mass number of 238 or less?
I have always been led to understand that the mass of an element on the periodic table is the weighted average atomic mass over all naturally occurring isotopes. This seems to make sense with all the elements I have looked at except for uranium.…
marktwo
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28
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3 answers
How to assign E/Z configuration according to the Cahn-Ingold-Prelog rules when subsituents differ only by stereochemistry
I stumbled-upon this compound:
I'm wondering how to determine the configuration of the double bond. Is it E or Z? How do I decide on the priorities when the substituents can only differ in the configurations on the chiral centers?
martin-is-my-name
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28
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2 answers
What do the quantum numbers actually signify?
I know how to calculate them and such stuff, but I wanted to know what they actually signify. I have a vague idea that they have something to do with an electron's position in an atom but what do all of them mean? Any help would be greatly…
Jyotinder Singh
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28
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Ripping apart plastic: is this a chemical or physical change?
I was holding a piece of plastic earlier, and I ripped it in half. This caused me to start to think about what was happening at the atomic level. If the plastic is being ripped, clearly bonds are being broken and new bonds are being formed, so is…
ringo
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28
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Why is lithium the most reducing alkali metal, and not caesium?
Caesium has a larger size, and the effective nuclear charge that the valence electron experiences will be far less compared to that of lithium's, right? But lithium is still considered the strongest reducing agent among all the alkali metals, and…
Yash Chowdhary
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28
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2 answers
How to find the second order perturbation to wave function?
Today, I'm looking for how to find the 2nd perturbation to the base in Rayleigh Schrödinger Perturbation Theory (RSPT).
SETUP
Starting from the 2nd order perturbation in Dirac's notation:
\begin{equation}
\hat{H}^0 |n^2\rangle + \hat{V} |n^1\rangle…
Another.Chemist
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28
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Why is 2-methylpropene less in energy than its alkene counterparts?
Other isomers include 1-butene, cis 2-butene, and trans 2-butene. Why would 2-methylpropene be less in energy if there is more steric hindrance?
CognisMantis
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28
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Why is ethyne and not ethene used for welding?
Ethyne (Acetylene) is used with $\ce{O2}$ for welding. My question is that why is ethene not used? What properties of ethyne make it suitable for welding?
Princess
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2 answers
Why is snow white?
I know that this is a rather ambiguous question; but my question is, whenever we take water and freeze it in the freezer, it still tends to stay clear. Since snow is just frozen water, why is it white? Is it due to contents of the air - i.e. dust -…
Asker123
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Why are there no cheap diamond equivalents?
We recently learned in school that diamonds sparkle as the are very optically dense, meaning that it takes longer for light to pass through them, thus meaning that the light totally internally reflects when you look at a diamond, whereas in glass it…
Deep
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28
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Why is water "the universal" solvent?
This is an old question that our textbook tried to answer but worsened the situation.
Many things are soluble in water. So many, that studying solutions will always require studying aqueous ones. It is true that many non-polars like waxes are not…
M.A.R.
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