Question

Explain by giving one example why do oxidation and reduction proceed side by side ?

Answer 1

1. Oxidation- It is defined as the gain of an oxygen atom or loss of a hydrogen atom or the loss of electrons during a reaction. During oxidation, the oxidation number of atoms increases.

Example: $$\begin{gathered} \mathrm{Na}\left(\mathrm{s}\right)\to {\mathrm{Na}}^{+}\left(\mathrm{g}\right)+{\mathrm{e}}^{-} \\ \mathrm{Sodium}\mathrm{Sodium}\mathrm{electron} \\ \mathrm{ion} \end{gathered}$$

or $$\begin{gathered} 2\mathrm{Mg}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2\mathrm{MgO}\left(\mathrm{s}\right) \\ \mathrm{Magnesium}\mathrm{Oxygen}\mathrm{Magnesium}\mathrm{oxide} \end{gathered}$$

2. Reduction- It is defined as the loss of an oxygen atom or gain of a hydrogen atom or the gain of electrons during a reaction. During reduction, the oxidation number of atoms decreases.

Example: $$\begin{gathered} {\mathrm{Cl}}_2\left(\mathrm{g}\right)+2{\mathrm{e}}^{-}\to 2{\mathrm{Cl}}^{-}\left(\mathrm{g}\right) \\ \mathrm{Chlorine}\mathrm{Chloride}\mathrm{ion} \end{gathered}$$

or

$$\begin{gathered} {\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{Br}}_2\left(\mathrm{g}\right)\to 2\mathrm{HBr}\left(\mathrm{g}\right) \\ \mathrm{Hydrogen}\mathrm{Bromine}\mathrm{Hydrogen}\mathrm{bromide} \end{gathered}$$

3. As oxidation involves the loss of the electrons, these lost electrons are gained by the other species, and that species experiences reduction after gaining these electrons.

Thus, oxidation and reduction proceed side by side.

4. Example-

$$\begin{gathered} {\mathrm{CuSO}}_4\left(\mathrm{aq}\right)+\mathrm{Zn}\left(\mathrm{s}\right)\to \mathrm{Cu}\left(\mathrm{s}\right)+{\mathrm{ZnSO}}_4\left(\mathrm{aq}\right) \\ \mathrm{Copper}\mathrm{Zinc}\mathrm{Copper}\mathrm{Zinc} \\ \mathrm{sulphate}\mathrm{sulphate} \end{gathered}$$

In this reaction, $\mathrm{Zn}$ is oxidized and loses two electrons which are gained by Copper ($\mathrm{Cu}$) of${\mathrm{CuSO}}_4$. Hence, oxidation and reduction occur side by side.