Justify that the reaction : `2 Na(s) + H_(2) (g) rarr 2NaH (s)` is a redox change.

Explanation

Since in the above reaction the compound formed is an ionic compound, which may also be represented as `Na^(+)H^(-) (s)`, this suggests that one half reaction in this process is :
`2 Na (s) rarr 2Na^(+) (g) + 2e^(-)` and the other half reaction is :
`H_(2) (g) + 2e^(-) rarr 2H^(-) (g)`
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.