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2 answers
What are some good examples of rate equations for a math class?
I'm a mathematician who's currently teaching a course on differential equations. Though I don't know much about chemistry, I like to include examples from chemistry in my course, and I prefer for the details to be accurate. Here is a typical exam…
Jim Belk
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26
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Why do we get slightly more inversion product than retention product in SN1 reaction?
Theoretically, in $\mathrm{S_N1}$ reaction we should get a racemic mixture as the product because the nucleophile can attack from either side of the formed carbocation.
However, many textbooks claim that there's slightly more inversion product than…
Ritwik Das
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26
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Solutions of Group 1 and Group 2 metals in Ammonia
When we add Group-1 and Group-2 metals to liquid ammonia, they dissolve to form metal cations and solvated electrons.
$$\ce{M + NH3(liq) -> M+ + e-}$$
Now, when the G-1 solutions evaporate, we get the metal back, but in the case of G-2 solutions…
Ayushmaan
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26
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Ambimodal transition states in some organic reaction pathways
In many computational studies, mechanisms appear to have so-called ambimodal transition states, i.e. a transition state which can lead to multiple products, in conflict to the common undergraduate idea of a reaction pathway.
To give an example,…
NotEvans.
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26
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4 answers
Relation between chemical kinetics and chemical equilibrium
In my chemistry book, the law of chemical equilibrium is derived from the law of mass action:
For a reversible chemical reaction $$\ce{aA +bB\rightleftharpoons cC + dD}$$ where $a$, $b$, $c$ and $d$ are stoichiometric coefficients in the balanced…
S R Maiti
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26
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5 answers
Why do branched chain compounds have lower boiling points than the corresponding straight chain isomers?
The branched chain compounds have lower boiling points than the corresponding straight chain isomers. For example,
$\ce{CH_3CH_2CH_2CH_2CH_3}$ -
No branching-Pentane (n-pentane) ($\mathrm{b.p.}=309~\mathrm{K}$)
$\ce{CH_3CH(CH_3)CH_2CH_3}$ -…
Sensebe
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26
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1 answer
Canonical MOs vs. Localized MOs: Do both represent reality in the same way?
In my understanding localized molecular orbitals (LMOs) are equivalent to "standard" molecular orbitals, often called canonical orbitals (CMOs—by the way, why are they called canonical?). We can produce LMOs by linear combination of CMOs and they…
DSVA
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26
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2 answers
How are the number of tetrahedral voids twice the number of octahedral voids in a CCP structure?
How are the number of tetrahedral voids twice the number of octahedral voids in a CCP structure? Is there some kind of mathematical proof for it? Is there some way I can understand this intuitively?
I have been trying to think about it using this…
Arishta
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26
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6 answers
Chirality of symmetrically substituted biphenyl
I am facing trouble with the following problem: is 2,6-dimethyl-2',6'-dinitro-1,1'-biphenyl chiral?
My idea is that there is a axis of symmetry along the line joining the two benzene molecules. Hence it should be achiral.
However my book states it…
Pink
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26
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2 answers
Why is chemical accuracy defined as 1 kcal/mol?
"Chemical accuracy" in computational chemistry, is commonly understood to be $1~\mathrm{kcal\over mol}$, or about $4~\mathrm{kJ\over mol}$. Spectroscopic accuracy is $1~\mathrm{kJ\over mol}$, and that definition has intuitive sense. However, where…
Samuel Tan
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26
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4 answers
Why is acetic acid more acidic than phenol?
Acetic acid (ethanoic acid, $\mathrm pK_\mathrm a \approx 5$) is more acidic than phenol ($\mathrm pK_\mathrm a \approx 10$), which is reflected in their reactivity with a weak base such as sodium carbonate (adding acetic acid leads to effervescence…
Manisha Poudel
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26
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2 answers
Is cis-1,2-dimethylcyclohexane a meso compound?
I was watching a video lecture today on hydrocarbons and came across this. The instructor says that, as there is a plane of symmetry, cis-1,2-dimethylcyclohexane is a meso-compound:
However, the cyclohexane ring is never planar as it adopts a chair…
user14857
26
votes
4 answers
How are solvents chosen in organic reactions?
Just reading through organic chemistry book (Modern Projects in Organic Chemistry by Mohrig, et al.), and it seems like the choice of solvent is usually arbitrary.
One of the experiments designed uses hypochlorite ion as the oxidizer and acetone as…
Ryan David Ward
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2 answers
How should I go about picking a functional for DFT calculations?
I've been looking to use time-dependent density functional theory, but reading the literature I keep getting overwhelmed by how many different functionals there are. How should I go about selecting which functional to use?
Dan
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26
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2 answers
What does lowercase r-s notation mean?
I came across a naming convention which I haven't seen before. I let ChemDraw name the following compound for me and got a name containing lowercase "r" and "s" configurations.
Can someone tell me what this means and something about the actual…
Philipp
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