Chapter 2, Problem 2.23P

Interpretation Introduction

Interpretation:

Why the nonpolar $\text{1, 4}-\text{dibromobenzene}$ has a higher boiling point than polar $\text{1, 2}-\text{dichlorobenzene}$ is to be explained.

Concept introduction:

The boiling point of a compound depends on the strength of the intermolecular forces that exist between its molecules. The main types of intermolecular interactions in increasing order of strength are induced dipole-induced dipole, dipole-dipole, and hydrogen bonding.

Polar molecules have both induced dipole-induced dipole interactions, and possibly hydrogen bonding too. Nonpolar molecules have only induced dipole-induced dipole interactions. Generally nonpolar molecules have weaker intermolecular interactions than polar molecules of comparable size.