Question

Classify the acids based on their basicity and give complete equation for their ionisation in water?

Answer 1

• The basicity of an acid is the number of hydrogen ions [H⁺] which can be produced per molecule of the acid in aqueous solution or the number of hydroxyl ions (of a base) with which one molecule of acid can combine.
• Based on basicity acid can be classified as monobasic, dibasic, tribasic so on.

1. Monobasic Acid

Acids which produce one hydronium ion per molecule of the acid by ionization with water are called monobasic.

Example: HCl(aq) + H₂O(aq) ⇢ H₃O⁺ (aq) + Cl^- (aq)

2. Dibasic Acid

Acids which produce two hydronium ion per molecule of the acid by ionization with water are called dibasic.

Example: H₂SO₄ (aq) + H₂O (aq) ⇢ H₃O⁺ (aq) + HSO₄^- (aq)

HSO₄^- (aq)+ H₂O (aq) ⇢ H₃O⁺ (aq) + SO4 ^2- (aq)

3. Tribasic Acid

Acids that produce three hydronium ions per molecule of the acid on ionization with water are called tribasic.

Example: H₃PO₄ (aq) + H₂O (aq)⇢ H₃O⁺ (aq)+ H₂PO₄^- (aq)

H₂PO4^- (aq) + H₂O(aq) ⇢ H₃O⁺ (aq) + HPO₄ ^2- (aq)

HPO₄ ^2- (aq) + H₂O (aq)⇢ H₃O⁺ (aq) + PO₄ ^3- (aq)