Identify the oxidizing agent in the following redox reaction.
Hg2+(aq) + Cu(s) → Cu2+(aq) + Hg(l)

The oxidizing agent in this reaction is Hg^+.

A redox reaction is one in which there is a change in oxidation number of chemical species from left to right in the reaction. The oxidizing agent is the specie that experiences a decrease in oxidation number while the reducing agent is the specie that experiences an increase in oxidation number.

Looking at the reaction; Hg^2+(aq) + Cu(s) → Cu^2+(aq) + Hg(l), the oxidation number of mercury decreased from +2 to zero hence it is the oxidizing agent in this reaction.

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Hg²⁺

Explanation:

In the given reaction, Hg²⁺ is the oxidizing agent in the reaction.

An oxidizing agent is any specie that undergoes reduction in the course of a reaction. Such specie;

The reaction               Hg²⁺  +  Cu       →      Cu²⁺    +   Hg

  here Hg, goes from an oxidation state of 2 to 0. This is a decrease