What Happens During Hydrolysis?

Hydrolysis is a chemical decomposition reaction involving water and another chemical that forms at least one new compound. Dissolving a salt, either of a weak base, weak acid or both, is the most common type of hydrolysis. The water in the reaction ionizes into OH- ions and H+ ions. H+ ions hydrate to form H3O+ ions. The salt also dissociates into positive and negative ions.

Sodium acetate readily dissolves in water, dissociating into sodium ions and acetate ions. Most of the sodium ions remain in the solution without reacting with the hydroxyl ions as sodium hydroxide is a strong base. However, acetic acid is a weak acid, and acetate ions react with the hydrogen ions to form neutral acetic acid molecules. The result of the reaction is an excess of hydroxyl ions that creates a basic solution. This hydration reaction causes a chemical reaction between the water and a dissolved salt.

Water is less reactive with other organic compounds. Adding strong acids or bases or the use of steam causes hydrolysis in some cases in which water does not. Manufacturers use hydrolysis reactions to synthesize alcohols from double bonded hydrocarbons. Ethene, or CH2CH2, reacts with water to result in ethanol, or CH3COOH, when manufacturers mix the two with a strong acid catalyst. Manufacturers convert vegetable oils and animal fats to glycerol or fatty acids using steam. Plants and animals also use hydrolysis to metabolize food.