The change in the oxidation state of iodine when axcess chlorine water is added to an iodide salt is

Answer

To determine the change in the oxidation state of iodine when excess chlorine water is added to an iodide salt, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Initial Oxidation State of Iodine**:
- In iodide salts (e.g., KI), iodine has an oxidation state of -1.

2. **Identify the Reaction with Chlorine Water**:
- When chlorine water (Cl2 in water) is added to iodide salts, a reaction occurs where iodine is oxidized. The relevant reaction can be represented as:
\[ 2KI + Cl_2 + 2H_2O \rightarrow 2I_2 + 2HCl + HIO_3 \]

3. **Determine the Final Oxidation State of Iodine**:
- In the product HIO3 (iodic acid), we need to determine the oxidation state of iodine. Let’s denote the oxidation state of iodine in HIO3 as \( x \).
- The equation for the oxidation state is:
\[ x + 3(-2) + 1 = 0 \quad \text{(since H is +1)} \]
- Simplifying this gives:
\[ x - 6 + 1 = 0 \implies x - 5 = 0 \implies x = +5 \]
- Therefore, the oxidation state of iodine in HIO3 is +5.

4. **Calculate the Change in Oxidation State**:
- The change in oxidation state of iodine when going from -1 to +5 is calculated as:
\[ \text{Change} = \text{Final Oxidation State} - \text{Initial Oxidation State} = +5 - (-1) = +5 + 1 = +6 \]

5. **Conclusion**:
- The change in the oxidation state of iodine when excess chlorine water is added to an iodide salt is +6.