Question

Arrange the following compounds in increasing order of their boiling points.
$C{H}_{3}CHO,C{H}_{3}C{H}_{2}OH,C{H}_{3}OC{H}_3,C{H}_{3}C{H}_{2}C{H}_3$

Answer 1

As the intermolecular force increases, boiling point increases. Strength of intermolecular force is as follows:
$H-\text{bonding}>\text{dipole-dipole}>\text{Dispersion force}$

Alcohol has the highest boiling point due to more extensive intermolecular $H-\text{bonding}$.
Aldehyde is more polar than ether. So, ethanal has higher boiling point than methoxy methane.

Alkane has the lowest boiling point due to complete non-polar nature(it has only London dispersion force).

Hence, increasing order of boiling points of compounds is given below-
$C{H}_{3}C{H}_{2}C{H}_3<C{H}_{3}OC{H}_3<C{H}_{3}CHO<C{H}_{3}C{H}_{2}OH$