What is hydrolysis of salt?

Hydrolysis of salt refers to a chemical reaction in which a salt reacts with water to produce an acidic or basic solution. This reaction occurs when the cation or anion of the salt undergoes hydrolysis, meaning it reacts with water to either donate or accept protons (H⁺ ions), resulting in the formation of an acidic or basic solution.

The pH of the resulting solution depends on the nature of the ions produced from the dissociation of the salt. There are three possible scenarios for the hydrolysis of salt:-

1. Salt of a Strong Acid and Weak Base: When a salt is formed from the reaction between a strong acid and a weak base, the cation of the salt will not undergo hydrolysis, but the anion will act as a weak base and react with water to produce hydroxide ions (OH⁻). This results in an alkaline (basic) solution.

2. Salt of a Weak Acid and Strong Base: Conversely, when a salt is formed from the reaction between a weak acid and a strong base, the anion of the salt will not undergo hydrolysis, but the cation will act as a weak acid and react with water to produce hydronium ions (H₃O⁺). This results in an acidic solution.

3. Salt of a Weak Acid and Weak Base: If both the cation and anion of the salt are derived from weak acid-base combinations, then both ions may undergo hydrolysis, leading to a solution with a pH that is slightly acidic, slightly basic, or neutral, depending on the relative strengths of the acid and base components.

Examples of salts undergoing hydrolysis include ammonium chloride (NH₄Cl), which produces a slightly acidic solution due to the hydrolysis of the ammonium ion, and sodium acetate (CH₃COONa), which produces a slightly alkaline solution due to the hydrolysis of the acetate ion.

Hydrolysis of salts is a fundamental concept in chemistry and is important in understanding the behavior of salt solutions in various chemical and biological processes.