Question

Identify reducing agent in following reaction:
$\text{H}_2\text{O}_{2(aq)} + \text{ClO}_{4(aq)}^- \rightarrow \text{ClO}_{2(aq)}^- + \text{O}_{2(g)}$

• A. $\text{ClO}_{2(aq)}^-$
• B. $\text{H}_2\text{O}_{2(aq)}$
• C. $\text{ClO}_{4(aq)}^-$
• D. $\text{O}_{2(g)}$

Hint:

In any chemical reaction where hydrogen peroxide ($\text{H}_2\text{O}_2$) yields oxygen gas ($\text{O}_2$), it is always undergoing oxidation (from $-1$ to $0$) and thus always acts as a reducing agent.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
We need to identify the reducing agent in the given redox reaction, which is the species that undergoes oxidation.

Step 2: Key Formula or Approach:
Track the oxidation numbers of the elements involved; the substance containing an element whose oxidation number increases acts as the reducing agent.

Step 3: Detailed Explanation:
In this reaction, the oxidation number of oxygen in H₂O₂ increases from -1 to 0 in O₂, meaning H₂O₂ is oxidized. Conversely, chlorine in ClO₄⁻ is reduced from +7 to +3 in ClO₂⁻. Thus, H₂O₂ is the electron donor and the reducing agent.

Step 4: Final Answer:
The reducing agent is H₂O₂(aq), which corresponds to option (B).