Short Answer TypeGive a brief account of the following processes as used in extraction of metals:
(a) Smelting
(b) Magnetic separation
What do you understand by the following terms: (i) Roasting, (ii) Calcination, (iii) Smelting?
i) Roasting: In roasting, the ore is heated in aregular supply of air in a furnace at a temperature below the melting point of the metal. For example:
2ZnS + 3O2 → 2ZnO + 2SO2
2PbS + 3O2 → 2PbO + 2SO2
2Cu2S + 3O2 → 2Cu2O + 2SO2
ii) Calcination: Calcination involves simple decomposition of ore on heating below its melting point usually in absence of air to produce new compounds having higher percentage of metal.
Fe2O3.xH2O(s)+heat → Fe2O3 (s) + xH2O(g)
ZnCO3 (s) +heat → ZnO(s) + CO2(g)
Long Answer TypeDescribe mainly with balanced chemical equations.
(a) Copper from copper pyrites by self reduction.
(b) Zinc from zinc blende by carbon reduction.
(c) Silver from silver glance by cyanide process.
(a) How is aluminium extracted from alumina?
(b) Give balanced equations for the extraction of aluminium from bauxite by electrolysis.
(c) What is the function of cryolite in the extraction of Al from Al2O3.
Short Answer Type
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