The correct option is **B. Cl2**. ### Step-by-Step Explanation: 1. **Understanding Oxidizing Agents**: - An oxidizing agent is a substance that gains electrons in a chemical reaction and, in the process, causes another substance to be oxidized. This means that the oxidizing agent itself is reduced. - In redox (reduction-oxidation) reactions, oxidation refers to the loss of electrons, while reduction refers to the gain of electrons. 2. **Analyzing the Given Reaction**: - The reaction provided is: \[ \text{H}_2\text{O} + 2\text{Fe}^{2+} + \text{Cl}_2 \leftrightarrow 2\text{Fe}^{3+} + 2\text{Cl}^- + \text{H}_2\text{O} \] - In this reaction, we need to identify which species is being reduced (gaining electrons) and which is being oxidized (losing electrons). 3. **Identifying Oxidation States**: - **Fe²⁺ to Fe³⁺**: The iron ion (Fe²⁺) is oxidized to Fe³⁺. This means it loses an electron: \[ \text{Fe}^{2+} \rightarrow \text{Fe}^{3+} + e^- \] - **Cl₂ to Cl⁻**: The chlorine molecule (Cl₂) is reduced to chloride ions (Cl⁻). This means it gains electrons: \[ \text{Cl}_2 + 2e^- \rightarrow 2\text{Cl}^- \] 4. **Determining the Oxidizing Agent**: - Since Cl₂ is gaining electrons (being reduced), it is acting as the oxidizing agent in this reaction. Therefore, Cl₂ is the correct answer. ### Why the Other Options are Incorrect: - **A. Fe²⁺**: - Fe²⁺ is being oxidized to Fe³⁺, meaning it is losing electrons. Therefore, it cannot be an oxidizing agent; it is a reducing agent instead. - **C. Fe³⁺**: - Fe³⁺ is the product of the oxidation of Fe²⁺. It does not participate in gaining electrons in this reaction, so it cannot be an oxidizing agent. - **D. Cl⁻**: - Cl⁻ is the product of the reduction of Cl₂. Since it has already gained electrons, it cannot act as an oxidizing agent; it is a reduced form of chlorine. ### Summary of Key Points: - An oxidizing agent gains electrons and causes another substance to be oxidized. - In the reaction, Cl₂ is reduced to Cl⁻, making it the oxidizing agent. - Fe²⁺ is oxidized to Fe³⁺, acting as a reducing agent. - Understanding oxidation states helps identify which species is oxidized and which is reduced. ### Revision Summary: - **Oxidizing agents gain electrons and are reduced.** - **Cl₂ is reduced to Cl⁻, making it the oxidizing agent.** - **Fe²⁺ is oxidized to Fe³⁺, acting as a reducing agent.** - **Identifying oxidation states is crucial for determining roles in redox reactions.**