Question

Explain in brief types of extraction of moderately reactive metals according to their reactivity.

Answer 1

Extraction of moderately reactive metals:

1. Moderately reactive metals such as iron, zinc, lead, copper usually occur in the form of their sulphide salts or carbonate.
2. It is easier to obtain metals from their oxides rather than sulphides or carbonates.
3. Therefore, the sulphide ores are strongly heated in excess of air to transform them into oxides. This process is called roasting.
   E.g. \[\ce{\underset{\text{Zinc sulphide}}{2ZnS_{(s)}} + 3O_{2(g)} -> \underset{\text{Zinc oxide}}{2ZnO_{(s)}} + \underset{\text{Sulphur dioxide}}{2SO2\uparrow}}\]
4. Carbonate ores are strongly heated in a limited supply of air to transform them into oxides. This process is called calcination.
   E.g. \[\ce{\underset{\text{Zinc carbonate}}{ZnCO_{3(s)}} ->[Heat] \underset{\text{Zinc oxide}}{ZnO_{(s)}} + \underset{\text{Carbon dioxide}}{CO2}}\]
5. The oxide so obtained is reduced to metal by using suitable reductant such as carbon.
   \[\ce{\underset{\text{Zinc oxide}}{ZnO_{(s)}} + \underset{\text{Carbon}}{C_{(s)}} ->[Heat] \underset{\text{Zink}}{Zn_{(s)}} + \underset{\text{Carbon monoxide}}{CO\uparrow}}\]
6. The metal thus obtained can be further refined electrolysis.