# Question #bd419

Dec 16, 2016

The major intermolecular forces between propanoic acid and heptane are dipole-induced dipole forces.

#### Explanation:

The formula of propanoic acid is

$\text{CH"_3"CH"_2"CO-OH}$

It has a highly polar $\text{OH}$ group.

The formula of heptane is

${\text{CH"_3"CH"_2"CH"_2"CH"_2"CH"_2"CH"_2"CH}}_{3}$

It is a nonpolar hydrocarbon, so its strongest intermolecular forces are London dispersion forces.

When the two liquids are mixed, the strong $\text{OH}$ dipole in the propanoic acid molecule can deform the electronic cloud of the heptane.

It induces a dipole in the heptane molecule, so the interaction is called a dipole-induced dipole force.

You would expect propanoic acid to be "insoluble" in heptane, but the dipole-induced dipole forces increase the solubility to about 6 g/100 g heptane.