Explain hydrogen bonding in carboxylic acids and its effect on their boiling points.

(N/A) $(i)$ Carboxylic acids contain the $-COOH$ functional group. In the carboxyl group,the oxygen atom is highly electronegative,creating a polar $C=O$ bond and an $O-H$ bond. This results in a partial positive charge on the hydrogen atom and a partial negative charge on the carbonyl oxygen,leading to the formation of intermolecular hydrogen bonds between carboxylic acid molecules.
$(ii)$ These intermolecular hydrogen bonds are strong enough that they are not completely broken even in the vapour phase. Consequently,most carboxylic acids exist as stable dimers in the vapour phase or in aprotic solvents. This association of molecules increases the effective molecular mass,which significantly raises the boiling points of carboxylic acids compared to alcohols or aldehydes of comparable molecular masses.