Question

During the preparation of Mohr’s salt solution (Ferrous ammonium sulphate), which of the following acid is added to prevent hydrolysis of Fe²⁺ ion:

Options

• Dilute nitric acid

• Dilute sulphuric acid

• Dilute hydrochloric acid

• Concentrated sulphuric acid

Answer 1

Dilute sulphuric acid

Explanation:

Fe²⁺ and Al³⁺ ions undergo hydrolysis; hence, while making aqueous solutions of ferrous sulphate and aluminium sulphate, 2-3 mL of dilute sulphuric acid are added to prevent the hydrolysis of these salts.