Why do alcohols have higher boiling points than haloalkanes of the same molecular mass?

Explanation

Alcohols undergo extensive intermolecular H-bonding. As a result, alcohols exist as associated molecules as shown below:

Quite a large amount of energy is needed to break these H-bonds. Therefore, the boiling points of alcohols are much higher than haloalkanes of comparable molecular mass because the molecules of haloalkanes are held together only by weak dipole-dipole and van der waals forces of attraction. for example, the b.p. of methyl chloride is 249 K while that of methanol is 337.5.