Question

Explain redox reactions on the basis of electron transfer. Give suitable examples.

Answer 1

The given reaction is a redox change. 

$$2\mathrm{Na}(\mathrm{s})+\mathrm{H}{\phantom{A}}_2(\mathrm{g})⟶2\mathrm{NaH}(\mathrm{s})$$

The half reaction is:

$$2\mathrm{Na}(\mathrm{s})⟶2\mathrm{Na}{\phantom{A}}^{+}(\mathrm{g})+2\mathrm{e}{\phantom{A}}^{-}$$

The other half reaction is:

$$\mathrm{H}{\phantom{A}}_2(\mathrm{g})+2\mathrm{e}{\phantom{A}}^{-}⟶2\mathrm{H}{\phantom{A}}^{-}(\mathrm{g})$$

This splitting of the reaction into two half-reactions automatically reveals here that sodium is oxidized, and hydrogen is reduced. Any substance which loses electron is oxidized and gains electron is reduced hence is the case of sodium and hydrogen atoms respectively. Hence, the complete reaction is a redox change.