Question

Give appropriate scientific reasons for the statements. Zinc oxide can be reduced to zinc by using carbon monoxide, but aluminium oxide cannot be reduced by a reducing agent.

Answer 1

Reactivity series is a series in which elements are arranged by their reactivity on the basis of their electrode potential.

1. Zinc is placed in the middle of the reactivity series. So, it is moderately reactive which is easily reduced by carbon as carbon is a good reducing agent.

$$\begin{gathered} \mathrm{ZnO}\left(\mathrm{s}\right)+\mathrm{CO}\left(\mathrm{g}\right)\to \mathrm{Zn}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right) \\ \mathrm{zinc}\mathrm{oxide}\mathrm{carbon}\mathrm{monoxide}\mathrm{zinc}\mathrm{carbon}\mathrm{dioxide} \end{gathered}$$

2. The oxide of active metals like aluminium is highly reactive towards oxygen, so cannot be reduced by carbon.

Hence, Zinc oxide can be reduced to zinc by using carbon monoxide, but aluminium oxide cannot be reduced by a reducing agent.