Question

(a) Name the method by which aluminium metal is extracted.
(b) Give the name and chemical formula of one ore of copper.
(c) How is zinc extracted from its carbonate or (calamine)? Explain with equations.

Answer 1

(a) Aluminium is extracted by electrolytic reduction from molten aluminium oxide.

(b) One of the ores of copper is copper glance. The formula of the ore is ${\mathrm{Cu}}_2\mathrm{S}$.

(c) Calamine, zinc carbonate $\left({\mathrm{ZnCO}}_3\right)$, can be extracted by calcination. As zinc is moderately reactive and is placed at the middle of the reactivity series, it can be reduced by carbon. The steps involved in the extraction of zinc are:
1. Concentrated carbonate of zinc is converted to its oxide by calcination. In this process, zinc carbonate ore is strongly heated in the absence of air to produce zinc oxide and carbon dioxide gas.

${\mathrm{ZnCO}}_3\left(s\right)\stackrel{\mathrm{Calcination}}{\to }\mathrm{ZnO}\left(s\right)+{\mathrm{CO}}_2\left(g\right)$

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.
$\mathrm{ZnO}\left(s\right)+C\left(s\right)\stackrel{\mathrm{reduction}}{\to }\mathrm{Zn}\left(s\right)+\mathrm{CO}\left(g\right)$