Physical Properties of Carboxylic Acids

Boiling points

1. The greater the number of carbons in the molecule, the higher the boiling point of a carboxylic acid.
2. The boiling points of carboxylic acids are higher than the alcohols of same number of carbons.

Solubility in water

1. The small molecule carboxylic acid such as methanoic acid and ethanoic acid is soluble in water.
2. The solubility of the bigger acids decreases as the size of the molecule increases. This is because the longer hydrocarbon “tails” of the molecules get between water molecules and break hydrogen bonds.