Question

Identify the reducing agent and oxidizing agent in the following reactions:

$\mathrm{CuO}+{\mathrm{H}}_2\to \mathrm{Cu}+{\mathrm{H}}_2\mathrm{O}$

Answer 1

1. Redox reactions

Reactions involving a loss of electrons causing an increase in the oxidation state of a species is called oxidation reactions. In reduction reactions, the addition of electrons occurs causing a decrease in the oxidation state. Reactions in which oxidation and reduction occur simultaneously are called redox reactions.

In a redox reaction, one reactant is oxidized and is called the reducing agent and the other reactant is reduced called the oxidizing agent. The oxidizing and reducing agents are identified from the change in the oxidation state of the species.

2. Identifying Oxidizing and reducing agents in the given reaction

$$\begin{gathered} \mathrm{CuO}\left(\mathrm{s}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)\to \mathrm{Cu}\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \\ \mathrm{Cuprous}\mathrm{Hydrogen}\mathrm{Copper}\mathrm{Water} \\ \mathrm{oxide} \end{gathered}$$

In the above reaction, the oxidation state of Copper $\left(\mathrm{Cu}\right)$ decreases from +2 in Cuprous oxide $\left(\mathrm{CuO}\right)$ to 0 in copper. Therefore, it undergoes reduction.

The oxidation state of Hydrogen $\left({\mathrm{H}}_2\right)$ increases from 0 in Hydrogen gas to +1 in water. Therefore, it undergoes oxidation.

Thus, Copper oxide (CuO) is an oxidizing agent and Hydrogen $\left({\mathrm{H}}_2\right)$ is a reducing agent.