Question

which best describes the oxidizing agent in this reaction? cl₂(aq) + 2br⁻(aq) → 2cl⁻(aq) + br₂(aq) ○ bromine (br) is the oxidizing agent because it gains an electron. ○ bromine (br) is the oxidizing agent because it loses an electron. ○ chlorine (cl) is the oxidizing agent because it gains an electron. ○ chlorine (cl) is the oxidizing agent because it loses an electron.

Explanation:

1. Recall the definition of an oxidizing agent: An oxidizing agent is a substance that gets reduced (gains electrons) and causes another substance to be oxidized (lose electrons).
2. Analyze the reaction \( \ce{Cl_{2}(aq) + 2Br^{-}(aq)

ightarrow 2Cl^{-}(aq) + Br_{2}(aq)} \):

• For \( \ce{Cl_{2}} \): Each \( \ce{Cl} \) atom in \( \ce{Cl_{2}} \) has an oxidation state of 0. In \( \ce{Cl^{-}} \), the oxidation state of \( \ce{Cl} \) is - 1. So, \( \ce{Cl} \) goes from an oxidation state of 0 to - 1, which means it gains an electron (reduction).
• For \( \ce{Br^{-}} \): The oxidation state of \( \ce{Br} \) in \( \ce{Br^{-}} \) is - 1, and in \( \ce{Br_{2}} \) it is 0. So, \( \ce{Br} \) loses an electron (oxidation).

1. Since the oxidizing agent is the one that is reduced (gains electrons), \( \ce{Cl_{2}} \) (or \( \ce{Cl} \)) is the oxidizing agent because it gains an electron. The first two options are incorrect because \( \ce{Br} \) is oxidized (loses electrons), so it is the reducing agent. The fourth option is incorrect because \( \ce{Cl} \) gains electrons, not loses them.

Answer:

C. Chlorine (Cl) is the oxidizing agent because it gains an electron.