Chapter 22, Problem 39A

Interpretation Introduction

Interpretation:

The reason for ethanol to have higher boiling point than aminoethane needs to be determined.

Concept introduction:

The boiling point of an organic compound depends on the structure of the compound and its molecular mass. Intermolecular forces in organic compounds also play an important role in determining the boiling point.

Explanation of Solution

The three important factors on which the boiling point of an organic compound depends are as follows:

1. Intermolecular forces such as hydrogen bonding, ionic, dipole-dipole and Van der Waals forces.
2. If number of carbon atoms in an organic compound increases, boiling point also increases.
3. If in an organic compound branching increases, boiling point will decrease.

The structural formulas of ethanol and aminoethane are as follows:

Here, O is more electronegative than N atom thus, the hydrogen bonding formed in the case of ethanol will be stronger than aminoethane. Also, due to higher electronegtaivity of O atom the dipole-dipole interactions in case of ethanol molecules will be more. This results in higher boiling point of ethanol than aminoethane.