explain giving equation, what happens when:
ZNCO3 is heated in the absence of air?
a mixture of CU2O and CU2S is heated?
The process of reduction of carbonate ores to oxides by heating in the presence of limited air is called calcination. Zinc occurs as carbonate ore zinc carbonate. When ZnCO3 is heated in the absence of air, it leads to the extraction of the oxide ore from the compound. i.e. ZnCO3, when heated in the absence of air, decomposes to give ZnO and CO2.
heat
ZnCO3.......... ZnO+CO2
Copper glance, sulphide ore of copper is heated in the current of air to Cu2O, which combines further with Cu2S to get copper metal.
The Heating of Cu2O and Cu2S will produce copper metal and sulphur dioxide gas and the balanced reaction will be as follows:
heat
2Cu2O + Cu2S -------> 6Cu + SO2