State the reaction:
Sulphur dioxide gas is passed through an aqueous solution of Fe(III) salt?

Explanation

To determine the reaction that occurs when sulfur dioxide gas (SO₂) is passed through an aqueous solution of iron(III) salt (Fe³⁺), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- We have sulfur dioxide gas (SO₂).
- We have an aqueous solution of iron(III) salt, which contains Fe³⁺ ions.

2. **Write the Initial Reaction**:
- When SO₂ is introduced to the Fe³⁺ ions in the solution, we can represent the reaction as:
\[ \text{SO}_2 + \text{Fe}^{3+} + \text{H}_2\text{O} \rightarrow ? \]

3. **Determine the Reaction Type**:
- SO₂ acts as a reducing agent, meaning it will reduce Fe³⁺ to Fe²⁺ while itself being oxidized.

4. **Write the Products**:
- The reduction of Fe³⁺ to Fe²⁺ occurs, and the sulfate ion (SO₄²⁻) is formed as a product along with hydrogen ions (H⁺):
\[ \text{Fe}^{3+} + \text{SO}_2 + \text{H}_2\text{O} \rightarrow \text{Fe}^{2+} + \text{SO}_4^{2-} + \text{H}^+ \]

5. **Balance the Reaction**:
- To balance the reaction, we need to ensure that the number of atoms and charges are equal on both sides. The balanced reaction can be written as:
\[ 2\text{Fe}^{3+} + \text{SO}_2 + 2\text{H}_2\text{O} \rightarrow 2\text{Fe}^{2+} + \text{SO}_4^{2-} + 4\text{H}^+ \]

### Final Reaction:
\[ 2\text{Fe}^{3+} + \text{SO}_2 + 2\text{H}_2\text{O} \rightarrow 2\text{Fe}^{2+} + \text{SO}_4^{2-} + 4\text{H}^+ \]