Salt Hydrolysis in Chemistry

Salt Hydrolysis

• Salt hydrolysis is the reaction of a salt with water, forming an acidic or basic solution. It depends on the ions in the salt.
• The cation or anion of the salt interacts with water, producing H+ or OH- ions.

Types of Salt Hydrolysis

1. Salts of Strong Acid and Strong Base

• Salts like NaCl and KNO3 do not hydrolyze.
• Both cation and anion are neutral, so no reaction with water.
• Solution: Neutral (pH = 7)

2. Salts of Weak Acid and Strong Base

• Example: Sodium acetate (CH₃COONa).
• The anion (from the weak acid) reacts with water to produce OH^- ions.
• Reaction: CH₃COO^- + H₂O ⇌ CH₃COOH + OH^-
• Solution: Basic (pH > 7)

3. Salts of Strong Acid and Weak Base

• Example: Ammonium chloride (NH₄Cl).
• The cation (from the weak base) reacts with water to produce H⁺ ions.
• Reaction: NH₄⁺ + H₂O ⇌ NH₃ + H₃O⁺
• Solution: Acidic (pH < 7)

4. Salts of Weak Acid and Weak Base

• Example: Ammonium acetate (CH₃COONH₄).
• Both the cation and anion react with water.
• The pH depends on the relative strengths of the weak acid and weak base.
• Solution: Can be acidic, basic, or neutral.

Degree of Hydrolysis

• The degree of hydrolysis is the fraction of salt that undergoes hydrolysis in solution.
• It depends on the nature of the salt and the concentration of the solution.

Hydrolysis Constant (Kh)

• Kh is the equilibrium constant for the hydrolysis reaction.
• For salts of weak acids and strong bases: Kh = Kw / Ka
• For salts of strong acids and weak bases: Kh = Kw / Kb
• For salts of weak acids and weak bases: Kh = Kw / (Ka * Kb)
• Kw is the ion product constant of water.
• Ka is the acid dissociation constant.
• Kb is the base dissociation constant.

Applications of Salt Hydrolysis

• Buffer Solutions: Maintain stable pH in chemical and biological systems.
• Food and Pharmaceuticals: Designing products with specific pH levels.
• Water Treatment: Controlling hydrolysis helps in water purification.

Explore the concept of salt hydrolysis and how different types of salts react with water. This quiz covers salts of strong and weak acids and bases, and their effects on pH levels. Test your knowledge on the reactive properties and outcomes of various salts.