Question

What type(s) of intermolecular force is (are) common to each of the following. (Select all that apply.)

1) Xe and methanol (CH3OH)
a)london-dispersion forces
b)dipole-dipole
c)hydrogen bonding

i put a and b but it was wrong


2)CH3OH and acetonitrile (CH3CN)
a)london-dispersion forces
b)dipole-dipole
c)hydrogen bonding

i got a b and c but it was wrong.

please explain why the answer that is correct is correct

thanks:):)

Answer 1

Both have London forces.
Xe can't be dipole-dipole although it can be dipole-induced dipole and your instructor might be counting that as b (but I don't think that is very probable). CH3OH has hydrogen bonds; obviously Xe has no H and it can't have hydrogen bonding. So I would go with a only.

For b.
Everything has London forces.
Both are polar (therefore dipoles) but not strong ones.
CH3OH forms hydrogen bonds with other molecules of CH3OH. I don't think CH3CN is likely to form H bonds with itself so I would go with a and b.