Physical Properties of Carboxylic Acids
1. Aliphatic carboxylic acids up to nine carbon atoms are colourless liquids at room temperature with unpleasant odours. The higher acids are wax like solids.
2. The lower carboxylic acids are freely miscible with water due to the presence of intermolecular hydrogen bonding with H2O molecules. However, the solubility in water decreases gradually due to increase in the size of alkyl group.
3. Monocarboxylic acids have higher boiling points as compared to the alcohols of comparable molecular masses due to the presence of stronger intermolecular hydrogen bonding as shown below.