What intermolecular forces are present in CH_3OH?

1 Answer
Jun 23, 2018

Well, you got hydrogen bound to the VERY ELECTRONEGATIVE oxygen atom....

Explanation:

And in such a scenario where hydrogen is bound to a strongly electronegative element, hydrogen bonding is known to occur….a special case of bond polarity...

We could represent the dipoles as...

H_3C-stackrel(delta^+)O-stackrel(delta^-)H

And in bulk solution, the molecular dipoles line up...and this is a SPECIAL case of dipole-dipole interaction, "intermolecular hydrogen bonding", the which constitutes a POTENT intermolecular force, which elevates the melting and boiling points of the molecule.

And so we got normal boiling points of...

CH_4 ;-164 ""^@C.

H_3C-CH_3 ;-89 ""^@C.

H_3C-OH ;+64.7 ""^@C.

H_3C-CH_2OH ;+78.5 ""^@C.

H-O-H ;+100.0 ""^@C.

Of course, dispersion forces operate between all molecules...but these are not the same magnitude as intermolecular hydrogen bonding....