Unit 5.3: Hydrolysis

Learning Objectives

• Determine the approximate pH (equal to, smaller than or larger than 7) of salts in salt hydrolysis.
• Define hydrolysis as the reaction of a salt with water.
• Hydrolysis of the salt of a weak acid and a strong base result in an alkaline solution i.e., the pH > 7. Examples of such salts are sodium ethanoate, sodium oxalate and sodium carbonate.
• Hydrolysis of the salt of a strong acid and a weak base result in an acidic solution i.e., the pH < 7. An example of such a salt is ammonium chloride.
• The salt of a strong acid and a strong bases does not undergo hydrolysis and the solution of the salt will be neutral i.e., pH = 7.

Hydrolysis

• Hydrolysis is the reaction of a salt with water.
• The hydrolysis of a salt of a strong acid and a weak base is acidic, pH<7.
• The hydrolysis of a salt of a weak acid and a strong base is basic, pH>7.
• The salt of a strong acid and a strong base does not undergo hydrolysis.