Question

The reaction that does not define calcination is:
A. ${\text{ZnC}}{{\text{O}}_{\text{3}}}\,\mathop \to \limits^\Delta {\text{ZnO}}\,{\text{ + }}\,{\text{C}}{{\text{O}}_{\text{2}}}$
B. ${\text{F}}{{\text{e}}_2}{{\text{O}}_{\text{3}}}{\text{.x}}{{\text{H}}_{\text{2}}}{\text{O}}\,\mathop \to \limits^\Delta {\text{F}}{{\text{e}}_2}{{\text{O}}_{\text{3}}}\,{\text{ + }}\,{\text{x}}{{\text{H}}_{\text{2}}}{\text{O}}\,$
C. ${\text{CaC}}{{\text{O}}_{\text{3}}}{\text{.MgC}}{{\text{O}}_{\text{3}}}\,\mathop \to \limits^\Delta {\text{CaO + }}\,{\text{MgO}}\,\,{\text{ + }}\,2\,{\text{C}}{{\text{O}}_{\text{2}}}\,$
D. ${\text{2}}\,{\text{C}}{{\text{u}}_2}{\text{S}}\,{\text{ + }}\,{\text{3}}\,{{\text{O}}_2}\,\mathop \to \limits^\Delta {\text{2C}}{{\text{u}}_2}{\text{O + }}\,{\text{2}}\,{\text{S}}{{\text{O}}_2}\,$

Answer 1

Calcination is a metal extraction method. Calcination is used for the extraction of the metal from carbonate or oxide ores. It is carried out in absence of oxygen.

Complete answer:
Calcination is used to extract metal from concentrated ore. First, the metal is converted to oxide and then these oxides are reduced to get metal.
Two methods are used for the conversion of metal to oxide:
1. Calcination
2. Roasting.

Calcination is used for the metals which are present in the form of carbonate or oxide. Calcination is the heating of metal in an environment that lacks oxygen. So, volatile matter removes leaving behind the oxide of metal only.
Zinc carbonate$({\text{ZnC}}{{\text{O}}_{\text{3}}})$ is heated in absence of oxygen so, the first reaction defines the calcination.
${\text{F}}{{\text{e}}_2}{{\text{O}}_{\text{3}}}{\text{.x}}{{\text{H}}_{\text{2}}}{\text{O}}$ is heated in absence of oxygen. Water is escaping forming iron oxide so the second reaction defines the calcination.
${\text{CaC}}{{\text{O}}_{\text{3}}}{\text{.MgC}}{{\text{O}}_{\text{3}}}$ is heated in absence of oxygen. Decomposition gives calcium oxide and magnesium oxide so the third reaction defines the calcination.
Copper sulphide $({\text{C}}{{\text{u}}_2}{\text{S}})$ is heated in the presence of oxygen and also it is not in carbonate or oxide form so, it not calcination.
So, heating so copper sulphide with the presence of oxygen does not represent calcination.

**Therefore, option (D) ${\text{2}}\,{\text{C}}{{\text{u}}_2}{\text{S}}\,{\text{ + }}\,{\text{3}}\,{{\text{O}}_2}\,\mathop \to \limits^\Delta {\text{2C}}{{\text{u}}_2}{\text{O + }}\,{\text{2}}\,{\text{S}}{{\text{O}}_2}$ is correct.

Note:**
Calcination and roasting both processes are only different in two ways. Calcination is used for metal carbonate and metal oxide whereas roasting is used for metal sulphide. Calcination takes place in absence of oxygen whereas roasting takes place in presence of oxygen. The heating of copper sulphide in presence of oxygen defines the roasting. Roasting of copper sulphide takes place in the Reverberatory furnace.