Potassium dichromate acts as a strong oxidizing agent in acidic solution. During this process, the oxidation state changes from

Options

A. `+6` to `+3`
B. `+6` to `+2`
C. `+3` to `+1`
D. `+2` to `+1`

Answer

To solve the question regarding the oxidation state change of potassium dichromate in acidic solution, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Compound**:
Potassium dichromate is represented as \( K_2Cr_2O_7 \). The relevant part for oxidation state changes is the dichromate ion \( Cr_2O_7^{2-} \).

2. **Determine the Oxidation State of Chromium in Dichromate**:
In the dichromate ion \( Cr_2O_7^{2-} \), we can calculate the oxidation state of chromium (Cr). The formula for calculating oxidation state is:
\[ \text{Oxidation state} = x + 7(-2) = -2 \]
where \( x \) is the oxidation state of chromium. Solving for \( x \):
\[ x - 14 = -2 \implies x = +6 \]
Thus, the oxidation state of chromium in potassium dichromate is +6.

3. **Identify the Change in Oxidation State**:
In acidic solution, potassium dichromate acts as a strong oxidizing agent and gets reduced. The chromium in \( Cr_2O_7^{2-} \) is reduced to \( Cr^{3+} \) in the reaction. Therefore, the oxidation state changes from +6 to +3.

4. **Write the Half-Reaction**:
The half-reaction for the reduction of dichromate in acidic medium can be written as:
\[ Cr_2O_7^{2-} + 14H^+ + 6e^- \rightarrow 2Cr^{3+} + 7H_2O \]
This shows that the chromium is reduced from +6 to +3.

5. **Conclusion**:
The oxidation state of chromium in potassium dichromate changes from +6 to +3 during the reaction in acidic solution.

### Final Answer:
The oxidation state changes from +6 to +3.

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