Question

In the following reaction, identify the substance that is oxidized and the substance that is reduced $\underset{\mathrm{Copper}\mathrm{oxide}}{\mathrm{CuO}\left(\mathrm{s}\right)}+\underset{\mathrm{hydrogen}\mathrm{gas}}{{\mathrm{H}}_2\left(\mathrm{g}\right)}\leftrightharpoons \underset{\mathrm{Copper}}{\mathrm{Cu}\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

Answer 1

Redox reaction:

1. A chemical reaction in which both oxidation and reduction take place is categorized as a redox reaction.
2. Oxidation is defined as a gain of oxygen, loss of electrons, or increase in the oxidation number.
3. Reduction is defined as the loss of oxygen, the gain of electrons, or the decrease in the oxidation number.
4. In this reaction copper is reduced as its oxidation number changes from $+2$ to $0$ and oxygen is also removed from copper oxide.

$\stackrel{+2}{\underset{\mathrm{copper}\mathrm{oxide}}{\mathrm{CuO}\left(\mathrm{s}\right)}}\to \stackrel{0}{\underset{\mathrm{Copper}}{\mathrm{Cu}\left(\mathrm{s}\right)}}$

5. On the other hand hydrogen is oxidized because its oxidation number changes from $0$ to $+2$ and also oxygen are added to hydrogen.

$\stackrel{0}{\underset{\mathrm{Hydrogen}}{{\mathrm{H}}_2\left(\mathrm{g}\right)}}\to \stackrel{+2}{\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}}$

Therefore, Copper is reduced and hydrogen is oxidized in the reaction.