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votes
3 answers
The impossibility of 100% ionic bond
Recently, I read the definition of oxidation state on Wikipedia. It read that a 100% ionic bond is impossible. So what does a 75% ionic and 25% covalent bond mean at all?
user55990
20
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1 answer
Are compounds containing active methylene groups positive for the haloform test?
Are compounds containing active methylene groups (e.g. 1,3-diketones) positive for the haloform test? Support your answer with a suitable explanation.
I was stuck on a certain question wherein a diketone was formed and I had to tell whether or not…
YourAverageEuler
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Why do methane molecules have 15 degrees of freedom?
I've just been learning a little thermal chemistry including the equipartition theorem. As part of this, my textbook discusses how to figure out the degrees of freedom for different chemicals.
The answer to one of the exercises says methane has 15…
leob
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What is the nature of the bonding in cyclotriphosphazene?
The bonding in $\ce{(NPCl2)3}$ (and other compounds of the form $\ce{(NPR2)3}$) has historically been described using the ‘Dewar island model’.
By analogy to benzene, $\ce{(NPCl2)3}$ is π-electron precise, containing 6-electrons in the π-system,…
NotEvans.
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Why don't alkynes undergo preferential anti bromination to the degree that alkenes do?
Alkenes, for the most part (unless there is a phenyl group or highly ionising solvent) undergo almost exclusively anti addition of bromine. However, under similar conditions alkynes, although undergo preferential anti-addition, it is not as…
xasthor
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20
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Is the proton the strongest acid?
Having looked at the various definitions of acids and bases and having refined my understanding of it after learning about the inadequacies of pKa and the novel use of the Hammett acidity function, I would like to ask if the bare proton is the…
Tan Yong Boon
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2 answers
Overall effective activation energy for parallel reactions
Today, I was solving a question from Chemical Kinetics.
Consider the following parallel, first order reactions:
$$\begin{align}
\ce{A -> P} \tag{1} \\
\ce{A -> Q} \tag{2}
\end{align}$$
with rate constants $k_1$ and $k_2$, and activation energies…
Jaideep Khare
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What causes the "Gd break" in the trend of lanthanide-EDTA formation constants?
Smith and Martell obtained a series of data for the binding of trivalent lanthanide ions, $\ce{Ln^3+}$, with various carboxylic acid ligands (amongst them the well-known EDTA).1 A graph of the formation constants is attached ($K_\mathrm{f} =…
orthocresol
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Observability of Orbitals and Orbital Energies
This question comes from some thoughts I had after reading this question.
First of all, is an orbital an observable? I know the answer to this question is no because there is no "single-orbital operator" or whatever you'd like to call this. I brig…
jheindel
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If SOCl2 reacts with alcohols via SNi, why doesn't POCl3?
A bit of a follow-up to Why is thionyl chloride preferred for preparing alkyl chlorides from alcohols?.
The reaction with $\ce{SOCl2}$ is also used instead of $\ce{PCl3}$ and $\ce{PCl5}$ when retention of stereochemistry is required. Phosphorus…
Linear Christmas
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What happens chemically to 5'-radiolabeled aqueous thyroxine (thyroid prohormone) when its I-131 undergoes beta+gamma decay?
Related to this question about $\ce{^{14}C}$ beta decay in $\ce{CO2}$, what happens when the $\ce{^{131}I}$ in radiolabeled thyroxine (thyroid prohormone, or "T$_4$") undergoes beta-plus-gamma decay to form $\ce{^{131}Xe}$?
In order to narrow the…
hBy2Py
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3 answers
Why is ammonium a weak acid if ammonia is a weak base?
$\ce{NH3}$ is a weak base so I would have expected $\ce{NH4+}$ to be a strong acid. I can't find a good explanation anywhere and am very confused. Since only a small proportion of $\ce{NH3}$ molecules turn into $\ce{NH4+}$ molecules, I would have…
Clangorous Chimera
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EZ-Water - Fraud or breakthrough?
Recently the quack medicine folks online have been promoting the research of a certain Dr. Gerald Pollack who claims to have discovered a "forth phase of water", and who has recently published a book on the said topic.
Although it's clear that his…
Nathaniel Bubis
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Carbometalation of alkenes
Alkynes are capable of undergoing carbometalation, e.g. with organocopper reagents:
Why don't the corresponding alkenes undergo analogous carbometalation reactions? Is β-elimination the issue?
EJC
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Open flame combustion in bizarro world
Humans typically achieve combustion by starting a chemical reaction of a fuel (often a carbon $\ce{C}$ containing fluid like methane $\ce{CH4}$), which is is brought into an an oxidizer (a gas containing $\ce{O}$, like air). For example, when you…
Nikolaj-K
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