When `ClO_3^-`, changes to`CI^-`

Options

A. It gains six electrons
B. It gains four electrons
C. It loses six electrons
D. It gains three electrons

Answer

To solve the problem of how the chlorate ion \( \text{ClO}_3^- \) changes to the chloride ion \( \text{Cl}^- \), we need to analyze the change in the oxidation state of chlorine during this transformation.

### Step-by-Step Solution:

1. **Identify the oxidation state of chlorine in \( \text{ClO}_3^- \)**:
- Let the oxidation state of chlorine be \( x \).
- The oxidation state of oxygen is typically \( -2 \).
- In \( \text{ClO}_3^- \), there are three oxygen atoms, contributing a total of \( 3 \times (-2) = -6 \).
- The overall charge of the ion is \( -1 \).
- Therefore, we can set up the equation:
\[ x - 6 = -1 \]
- Solving for \( x \):
\[ x = -1 + 6 = +5 \]
- Thus, the oxidation state of chlorine in \( \text{ClO}_3^- \) is \( +5 \).

2. **Identify the oxidation state of chlorine in \( \text{Cl}^- \)**:
- In \( \text{Cl}^- \), the oxidation state of chlorine is \( -1 \).

3. **Determine the change in oxidation state**:
- The change in oxidation state from \( +5 \) in \( \text{ClO}_3^- \) to \( -1 \) in \( \text{Cl}^- \) can be calculated as follows:
\[ \text{Change} = \text{Final state} - \text{Initial state} = -1 - (+5) = -1 - 5 = -6 \]
- This indicates that the chlorine atom has gained 6 electrons.

4. **Conclusion**:
- Since the oxidation state of chlorine decreases from \( +5 \) to \( -1 \), it means that chlorine is being reduced. In reduction, a species gains electrons.
- Therefore, \( \text{ClO}_3^- \) gains 6 electrons to become \( \text{Cl}^- \).

### Final Answer:
The correct option is that \( \text{ClO}_3^- \) gains 6 electrons to become \( \text{Cl}^- \).

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