Question

Identify the substances that are oxidised and the substances that are reduced in the following reactions.
(i) `4Na(s)+O_(2)(g)rarr2NaO(s)`
(ii) `CuO(g) +H_(2)(g) rarr Cu(s) +H_(2)O(l)`

Answer 1

(i) In this reaction, sodium (Na) is oxidised to sodium oxide `(Na_(2)O)`. This means that oxygen `(O_(2))` has been reduced.
(ii) In this reaction, hydrogen `(H_(2))` is oxidised to water `(H_(2)O)` while copper (II) oxide `(CuO)` is reduced to copper `(Cu)`.