Question

Justify that the reaction:

$2Na\left(s\right)+H_2\left(g\right)\to 2NaH\left(s\right)$ is a redox change.

Answer 1

Since in the above reaction the compound formed is an ionic compound, which may also be represented as $N{a}^{+}{H}^{–}\left(s\right),$ this suggests that one half reaction in this process is :

$2Na\left(s\right)\to 2N{a}^{+}\left(g\right)+2e^{-}$

And the other half reaction is:

$H_2\left(g\right)+2e^{-}\to 2H^{-}\left(g\right)$

This splitting of the reaction under examination into two half reactions automatically reveals that here sodium is oxidised and hydrogen is reduced, therefore, the complete reaction is a redox change.