Mohr's salt is dissolved in dil. `H_(2)SO_(4)` instead of distilled water to

Options

A. Enhance the rate of dissolution
B. Prevent cationic hydrolysis
C. Increase the rate of ionisation
D. Increase its reducing strength

Answer

To solve the question regarding why Mohr's salt is dissolved in dilute H₂SO₄ instead of distilled water, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding Mohr's Salt**:
- Mohr's salt is a double salt, specifically ammonium iron(II) sulfate, represented as (NH₄)₂SO₄·FeSO₄·6H₂O. It contains both ammonium ions (NH₄⁺) and iron(II) ions (Fe²⁺).

2. **Dissolution in Water**:
- When Mohr's salt is dissolved in water, it dissociates into its constituent ions: NH₄⁺, Fe²⁺, and SO₄²⁻.

3. **Hydrolysis of Cations**:
- The cations present in Mohr's salt, particularly Fe²⁺ and NH₄⁺, can undergo hydrolysis. Hydrolysis is a reaction with water that can lead to the formation of acidic solutions.
- For example, Fe²⁺ can react with water to form Fe(OH)⁺ and release H⁺ ions, leading to an acidic environment.

4. **Effect of Hydrolysis**:
- The hydrolysis of these cations can affect the stability and the properties of the solution. It can lead to changes in pH and can complicate further reactions.

5. **Using Dilute H₂SO₄**:
- When Mohr's salt is dissolved in dilute sulfuric acid (H₂SO₄), the presence of H⁺ ions from the acid suppresses the hydrolysis of the cations.
- The H⁺ ions react with the hydroxide ions produced during hydrolysis, effectively preventing the formation of hydroxides and maintaining a stable solution.

6. **Conclusion**:
- Therefore, Mohr's salt is dissolved in dilute H₂SO₄ instead of distilled water to prevent the hydrolysis of its cations, ensuring the solution remains stable and does not become acidic due to the release of H⁺ ions from hydrolysis.

### Final Answer:
Mohr's salt is dissolved in dilute H₂SO₄ instead of distilled water to prevent the hydrolysis of its cations, which would lead to an acidic solution.