Question

Match the following reactions with the process involved during the extraction of moderately reactive metals.

• A. Roasting
• B. Calcination
• C. Reduction with carbon

Answer 1

Moderately reactive metals mostly exist as sulphide or carbonate ores. These can be extracted by:

$\bullet$ Sulphide ores are converted into oxides by roasting. These ores are heated in presence of excess air below its melting point. For example:

$2\mathrm{ZnS}\left(s\right)+3O_2\left(g\right)\to 2\mathrm{ZnO}\left(s\right)+2{\mathrm{SO}}_2\left(g\right)$

$\bullet$ Carbonate ores are converted into their oxides by the process of calcination. Ores are heated in the absence of air below its melting point. For example:

${\mathrm{CaCO}}_3\left(s\right)\to \mathrm{CaO}\left(s\right)+{\mathrm{CO}}_2\left(g\right)$

$\bullet$ After the ores are converted into their oxides, they are reduced with reducing agent like carbon to get the respective metal. For example:

$\mathrm{PbO}\left(s\right)+C\left(s\right)\to \mathrm{Pb}\left(s\right)+\mathrm{CO}\left(g\right)$