To determine which species is the oxidizing agent in the given reaction, we need to understand the concepts of oxidation and reduction:
[tex]\[
Cl_2(aq) + 2Br^-(aq) \rightarrow 2Cl^-(aq) + Br_2(aq)
\][/tex]
Oxidation is the process of losing electrons.
Reduction is the process of gaining electrons.
* The oxidizing agent is the substance that gets reduced (i.e., it gains electrons).
Let's analyze the reaction step by step:
1. Identify the oxidation states of the elements in the reaction:
- \( Cl_2 \): Each chlorine atom is in the 0 oxidation state in \( Cl_2 \) because it is in its elemental form.
- \( Br^- \): Each bromine ion is in the -1 oxidation state.
- \( Cl^- \): Each chloride ion is in the -1 oxidation state.
- \( Br_2 \): Each bromine atom in \( Br_2 \) is in the 0 oxidation state.
2. Determine the change in oxidation states:
- Chlorine (\( Cl_2 \)) changes from 0 to -1 by gaining electrons. This is a reduction process.
- Bromide ions (\( Br^- \)) change from -1 to 0 by losing electrons. This is an oxidation process.
3. Identify the species involved in the redox processes:
- Chlorine (\( Cl_2 \)) is reduced since its oxidation state decreases from 0 to -1.
- Bromide (\( Br^- \)) is oxidized since its oxidation state increases from -1 to 0.
4. Determine the oxidizing agent:
- The oxidizing agent is the substance that gets reduced, which means it gains electrons.
In this reaction:
- Chlorine (\( Cl_2 \)) gets reduced to chloride ions (\( Cl^- \)) by gaining electrons.
Therefore, the correct description of the oxidizing agent is:
- Chlorine (\( Cl \)) is the oxidizing agent because it gains an electron.
Thus, from the options provided, the correct choice is:
- Chlorine (\( Cl \)) is the oxidizing agent because it gains an electron.
Given the initial analysis and understanding of the redox process, we can conclude that the answer is:
[tex]\[
\boxed{3}
\][/tex]
