Question

(a) Name the method of refining which is
(i) Used to obtain semiconductor of high purity.
(ii) Used to obtain low boiling metal.
(b) Write chemical reactions taking place in the extraction of copper from $C{u}_{2}S$.

Answer 1

(a)
(i)The refining method used to obtain semi-conductors such as germanium, silicon and gallium of high purity is Zone Refining.

(ii)Distillation process is used to obtain metals which have low boiling point like zinc and mercury. In this method, the impure metal is heated to its boiling point in a vessel. The vapours of metal thus formed are collected and cooled in a separate vessel to get pure metal.

(b)
The sulphide ores are roasted to give oxides
$2C{u}_{2}S+3O_2⟶2C{u}_{2}O+2S{O}_2$
The oxide can easily be reduced to metallic copper using coke
$C{u}_{2}O+C⟶2Cu+CO$