The aqueous solution of `AlCl_(3)` is acidic due to the hydrolysis of

Options

A. Aluminium ion
B. Chloride ion
C. Both aluminium and chloride ion
D. None of these

Answer

To understand why the aqueous solution of AlCl₃ is acidic due to hydrolysis, we can break down the process step by step:

### Step 1: Understanding AlCl₃
AlCl₃, or aluminum chloride, is a salt formed from the reaction of aluminum hydroxide (a weak base) and hydrochloric acid (a strong acid). When dissolved in water, it dissociates into aluminum ions (Al³⁺) and chloride ions (Cl⁻).

### Step 2: Dissociation of AlCl₃
When AlCl₃ is added to water, it dissociates as follows:
\[ \text{AlCl}_3 (s) \rightarrow \text{Al}^{3+} (aq) + 3 \text{Cl}^- (aq) \]

### Step 3: Hydrolysis of Al³⁺
The aluminum ion (Al³⁺) is a small, highly charged cation. It has a strong tendency to attract water molecules, leading to hydrolysis. The hydrolysis reaction can be represented as:
\[ \text{Al}^{3+} (aq) + 6 \text{H}_2\text{O} (l) \rightleftharpoons \text{[Al(H}_2\text{O)}_6]^{3+} (aq) \]
This complex ion can further release protons (H⁺) into the solution, causing the solution to become acidic:
\[ \text{[Al(H}_2\text{O)}_6]^{3+} (aq) \rightleftharpoons \text{[Al(H}_2\text{O)}_5\text{OH}]^{2+} (aq) + \text{H}^+ (aq) \]

### Step 4: Resulting Acidity
The release of H⁺ ions into the solution results in an increase in the concentration of hydrogen ions, which lowers the pH of the solution, making it acidic.

### Conclusion
Thus, the aqueous solution of AlCl₃ is acidic due to the hydrolysis of Al³⁺ ions, which leads to the formation of H⁺ ions in the solution.

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