(a) Name the metal which is extracted from the ore called ‘rock salt’.
(b) Name two ores of zinc. Write the names of the chemical compounds present in them and give their chemical formulae.
(c) Explain how, mercury is extracted from its sulphide ore (cinnabar). Give equations of the reactions involved.
(d) In the electrolytic refining of a metal M, what would you take as anode, cathode and electrolyte?
(e) Name any five metals which are purified by electrolytic refining method.
(a) Sodium.
(b) (i) Calamine; Zinc carbonate, ZnCO3
(ii) Zinc blende; Zinc sulphide, ZnS
(c) Mercury (II) sulphide ore is roasted in air when mercury (II) oxide is formed.
2HgS(s) + 3O2(g) + Roasting → 2HgO(s) + 2SO2
When this mercury (II) oxide is heated to about 300°C, it decomposes to form mercury metal.
2HgO(s) + Heat + Reduction → 2Hg(l) + O2
(d) Anode - Thick block of impure metal M
Cathode - Thin strip of pure metal M
Electrolyte – Water soluble salt (of metal M).
(e) (i) Copper
(ii) Zinc
(iii) Nickel
(iv) Gold
(v) Silver