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1500 questions
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How can the intense color of potassium permanganate be explained with molecular orbital theory?
In the permanganate ion, manganese is in the $+7$ oxidation state, therefore it is a $\ce{d^0}$ ion. $\ce{d^0}$ and $\ce{d^1^0}$ ions don't absorb visible spectrum radiation because there are no electrons to jump to higher crystal field orbitals (or…
Nilay Ghosh
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Does nitrogen inversion affect the basicity of amines?
If I were to compare the basic strength of 1-azabicyclo[2.2.1]heptane and triethylamine:
Can I say that 1-azabicyclo[2.2.1]heptane is more basic than triethylamine because the lone pair of electrons is less available in the latter due to rapid…
Aditya Dev
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Why is trans-cyclooctene chiral?
How does trans-cyclooctene exhibit chirality if there are no stereocenters?
Related follow-on questions:
Are all higher cycloalkenes chiral?
Do more double bonds cause a bigger number of stereoisomers in cycloalkenes?
EJC
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Physical intuition behind negative values for wave function?
So a positive and a positive wave function create a bonding orbital where the probability of finding an electron is summed while a positive and a negative create an anti-bonding orbital with a lower electron probability in the region between them…
norlesh
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Why does a mixture of siloxene and cerium(IV) sulfate luminesce?
I performed an experiment where siloxene and cerium(IV) sulphate were mixed together: when I did so the mixture produced an orange-yellow glow. Why does it glow? What is it about the two chemicals in particular that makes this happen?
Method for…
Beta Decay
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4 answers
How does oil on the surface of water prevent rust?
I distinctly remember a side-by-side comparison from a book where there are two nails submerged in water, in two beakers: one nail had a layer of oil on top of the water, and that nail didn't rust; the other did.
It seems that oiling iron/steel…
Zubo
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6 answers
Why are equations of state for a non-ideal gas so elusive?
The ideal gas equation (daresay "law") is a fascinating combination of the work of dozens of scientists over a long period of time.
I encountered Van der Waals interpretation for non-ideal gases early on, and it was always somewhat in a…
jonsca
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What causes that foul taste with combination of toothpaste and orange juice?
Ugh, I drank orange juice too soon after brushing my teeth and my mouth feels awful!
What causes that foul taste with this combination of toothpaste and orange juice? Is it a reaction between the oil of wintergreen in the toothpaste and the citric…
Eliseo D'Annunzio
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How were old style stereographic structures produced?
Old papers on chemical structures often contained "3D" renderings of the molecule by using 2 2D images and requiring the reader to go cross-eyed to get the 3D image. A good example I recently found was figure 2 from Carter and Kraut, 1974, which I…
user137
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3 answers
Why can there not be more than one sigma bond in a set of bonds?
A question on an exam asked why there is exactly one sigma bond in double and triple covalent bonds. I looked in my text and online after the exam, but couldn't find an anawer to the question.
Why can there not be more than one sigma bond in a set…
Hal
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How can an inexperienced chemist determine the chemical structure of a molecule?
I'm a fairly inexperienced, but nonetheless interested chemist, currently planning a small project for the coming summer: I want to isolate an unknown chemical from a plant and determine it's chemical structure.
I have ample access to Carex grayi,…
user16651
25
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1 answer
How can I determine if there are π-π interactions between an amide and an aromatic ring in a protein?
In a crystal structure I've determined, a triazole ring on my ligand appears to be stacking with a tyrosine (top in picture):
However, there is also an amide, courtesy a glutamine, near it (bottom). Is it likely this terminal amide is engaging in…
Nick T
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3 answers
Why shouldn't Uranium come in contact with water?
In the documentary about Chernobyl, it was mentioned that Uranium should not come in contact with water, otherwise an explosion occurs. What is the reason for that? What kind of reaction makes it explode?
Ali Yucel Akgul
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2 answers
How is the pKa of extremely weak acids determined?
According to Wikipedia, the conjugate acid of LDA has a pKa of about 35 - which is in line with figures I've seen elsewhere.
How then can such a weak acid's pKa be determined? If the determination is made in water, how is that even possible? Water…
Dissenter
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5 answers
Why does radium have a higher first ionisation energy than barium?
I'm wondering why radium appears to buck the general trend that first ionisation energies decrease as you move down a group in the periodic table: barium (the group 2 element preceding it) has a first ionisation energy of $\pu{502.9 kJ/mol}$,…
Alicia Butteriss
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