Question 65
Two ores A and B were taken. On heating, ore A gives ${\text{CO}}_2$ whereas, ore B gives ${\text{SO}}_2$. What steps will you take to convert them into metals ?

Since ore A gives ${\text{CO}}_2$ and ore B gives ${\text{SO}}_2$, ore A is a carbonate, ${\text{MCO}}_3$, and ore B is a sulphide, $\text{MS}$.

Metal from ore A can be obtained by calcination, followed by reduction:
${\text{MCO}}_3\text{(s)}\stackrel{\text{Calcination}}{\to }\text{MO(s)}+{\text{CO}}_2\text{(g)}$
$\text{MO(s)}+\text{C(s)}\stackrel{\text{Reduction}}{\to }\text{M(s)}+\text{CO(g)}$

Metal from ore B can be obtained by roasting followed by reduction:
$2\text{MS(s)}+3{\text{O}}_2\text{(g)}\stackrel{\text{Roasting}}{\to }2\text{MO(s)}+2{\text{SO}}_2\text{(g)}$
$\text{MO(s)}+\text{C(s)}\to \text{M(s)}+\text{CO(g)}$