Question

Describe with one example, how moderately reactive metals (which are in the middle of reactivity series) are extracted.

Answer 1

The oxides of moderately reactive metals like zinc, iron, lead copper, placed in the middle of the reactivity series, are reduced by carbon because carbon is more reactive.

Let us take an example of extraction of zinc from its carbonate ore, i.e., calamine.
The steps involved in the extraction of concentrated calamine ore are:

1. Carbonate of zinc is converted to its oxide by calcination process. In calcination process, zinc carbonate ore is heated strongly in the absence of air to produce zinc oxide and carbon dioxide gas.
$$\begin{gathered} {\mathrm{ZnCO}}_3\underset{\mathrm{Absence}\mathrm{of}\mathrm{air}}{\overset{\mathrm{Calcination}}{\to }}\mathrm{ZnO}+{\mathrm{CO}}_2 \\ \mathrm{Zinc}\mathrm{carbonate}\mathrm{Zinc}\mathrm{Oxide}\mathrm{Carbon}\mathrm{dioxide} \\ (\mathrm{Calamine}\mathrm{ore}) \end{gathered}$$

2. Zinc oxide is then reduced by coke (carbon). When zinc oxide is heated with coke, carbon acts as a reducing agent and reduces zinc oxide to zinc metal.
$$\begin{gathered} \mathrm{ZnO}+\mathrm{C}\stackrel{\mathrm{Reduction}}{\to }\mathrm{Zn}+\mathrm{CO} \\ \mathrm{Zinc}\mathrm{Oxide}\mathrm{Coke}\mathrm{Zinc}\mathrm{metal}\mathrm{Carbon}\mathrm{monoxide}\mathrm{gas} \\ (\mathrm{reducing}\mathrm{agent}) \end{gathered}$$