Permanent Dipole-Dipole Interactions vs Induced Dipole Interactions. Who’s stronger?

Hoho

The idea is interesting but I would much rather see the worked-out equations than cartoons+hand waving. The heart of the discussion, which is that random temperature fluctuations produce randomized rotations, effectively canceling out electrostatic attractions, is a simple exercise in statistical mechanics. It’d be an important problem to tackle and the cartoons are not a compelling approach.

Furthermore your arguments are nearly good enough to make such a strong conclusion. “In real liquids, permanent dipole-dipole interactions actually play less important role than induced dipoles”? You cannot pick and choose your experiments just to emphasize this fact while ignoring the VAST amount of conflicting literature. Your statement is only feasibly valid in molecules large in 1 or 2 dimensions, (polymers, beta-sheets). If you do a good enough job working out the details I think your ideas may be quite important, but this webcomic is, IMO, bad science.

Hoho

“Furthermore your arguments are nearly good enough to make such a strong conclusion”

*are not
http://www.jkwchui.com/ Jon

Hi Hoho,

Thanks for the feedback. Mea culpa: I should have clarified that none of this is “my idea” (and certainly none of it is new science). The p-chem with derivations can be found in most phys chem textbook (e.g. Atkins). For this reason, I’m curious about the conflicting literature – can you point me to some examples in isotropic liquids where contributions from permanent dipole is more important than LDF? (Water is the only one that I remember being an exception (even after discounting for h-bonding), with its high polarity and low polarizibility.)

I’m also confused about the statement regarding polymer/beta-sheets. Those are precisely where I’d expect the contribution of permanent dipoles being non-negligible, since there is restriction of molecular motions. Could you clarify?

J