Aqueous solution of potash alum is acidic due to the hydrolysis of

Options

A. `K^(+)`
B. `Al^(3+)`
C. `SO_(4)^(2-)`
D. `Mg^(2+)`

Answer

To solve the question regarding the acidity of an aqueous solution of potash alum, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Composition of Potash Alum**:
Potash alum is chemically represented as KAl(SO4)2·12H2O. It consists of potassium sulfate and aluminum sulfate.

2. **Understand Hydrolysis**:
Hydrolysis is a reaction involving the breaking down of a compound by water. In the case of potash alum, when it dissolves in water, it dissociates into its constituent ions.

3. **Dissociation of Potash Alum**:
When potash alum is dissolved in water, it dissociates into:
- K⁺ (potassium ions)
- Al³⁺ (aluminum ions)
- SO₄²⁻ (sulfate ions)

4. **Focus on Aluminum Ions**:
Among these ions, the aluminum ion (Al³⁺) is a key player in the acidity of the solution. Aluminum ions can undergo hydrolysis, forming Al(OH)₃ and releasing H⁺ ions into the solution.

5. **Hydrolysis Reaction**:
The hydrolysis of Al³⁺ can be represented as:
\[ \text{Al}^{3+} + 3 \text{H}_2\text{O} \rightleftharpoons \text{Al(OH)}_3 + 3 \text{H}^+ \]
This reaction shows that aluminum ions react with water to produce hydroxide ions and hydrogen ions, leading to an increase in the concentration of H⁺ ions, which makes the solution acidic.

6. **Conclusion**:
Therefore, the aqueous solution of potash alum is acidic due to the hydrolysis of aluminum ions (Al³⁺).

### Final Answer:
The aqueous solution of potash alum is acidic due to the hydrolysis of **Al³⁺ ions**.

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