Write the role of the following :
(i) CO in the purification of nickel.
(ii) Graphite rod in the electrometallurgy of aluminium
Dear Student,
ii)
ii)
Inthe electrometallurgy of aluminium, a fused mixture of purifiedalumina (Al 2 O 3 ),cryolite (Na 3 AlF 6 )and fluorspar (CaF 2 )is electrolysed. In this electrolysis, graphite is used as the anodeand graphite-lined iron is used as the cathode. During theelectrolysis, Al is liberated at the cathode, while CO and CO 2 are liberated at the anode, according to the following equation.
If ametal is used instead of graphite as the anode, then O 2 will be liberated. This will not only oxidise the metal of theelectrode, but also convert some of the Al liberated at the cathodeback into Al 2 O 3 .Hence, graphite is used for preventing the formation of O 2 at the anode. Moreover, graphite is cheaper than other metals.
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Regards
Regards