Cliffs AP Chemistry, 3rd Edition

Samples: Multiple-Choice Questions

For Samples 1–5, use the following choices:

A. Hydrogen bonding

B. Metallic bonding

C. Ionic bonding

D. Dipole forces

E. van der Waals forces (London dispersion forces)

1. What accounts for the intermolecular forces between CCl 4 molecules?

Answer: E

Because CCl 4 is a nonpolar molecule, the only forces present are dispersion forces.

2. What explains why the boiling point of acetic acid, CH 3 COOH, is greater than the boiling
   point of dimethyl ether, CH 3 ΟCH 3?

Acetic acid, CH 3 COOH

Dimethyl Ether, CH 3 -O-CH 3

Answer: A

Note that for acetic acid there is a hydrogen attached to an oxygen atom (a prerequisite for H
bonding) but that for dimethyl ether there is no H atom connected to an F, O, or N atom.

Note: Had a choice been acetone, CH 3 COCH 3 , it would not have been

a good choice, since even though there is no hydrogen atom attached to an F, O, or N atom,
acetone enol is in tautomeric equilibrium with the ketone tautomer, resulting in a small amount
of hydrogen bonding, accounting for a higher than expected boiling point.

H

CC

H

H

O H

H C H

H

CO

H

H

H

H C H

H

CC

H O

H O H

Liquids and Solids