Question

Give two examples of reduction.

Answer 1

1. Reduction and oxidation

Reduction is the process of removal of oxygen and the addition of hydrogen. In this process, an atom or molecule gains one or more electrons.

Oxidation is the process of the addition of oxygen and the removal of hydrogen. Electrons are gained by an atom or the molecule participating in the reaction.

2. Examples of reduction

(i) Reaction of Copper oxide with magnesium to form Magnesium oxide and copper.

$$\begin{gathered} \mathrm{CuO}\left(\mathrm{s}\right)+\mathrm{Mg}\left(\mathrm{s}\right)\to \mathrm{MgO}\left(\mathrm{s}\right)+\mathrm{Cu}\left(\mathrm{s}\right) \\ \mathrm{Copper}\mathrm{Magnesium}\mathrm{Magnesium}\mathrm{Copper} \\ \mathrm{oxide}\mathrm{oxide} \end{gathered}$$

In the above reaction, Copper oxide is reduced to copper after losing oxygen.

(ii) Reduction of Copper oxide when it reacts with hydrogen gas:

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

The reaction shows the addition of hydrogen with oxygen and the removal of oxygen from Copper oxide.