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The following questions relate ta the extraction of aluminium by electrolysis: (i) Name the other aluminium containing compound added to alumina and state its significance. (ii) Give the equation for the reaction that takes place at the cathode. (iii) Explain why is it necessary to renew the anode periodically. |
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Answer» (i) Cryolite Molten cryolite acts as solvent for alumina,lowers the fusion temperature from 2050oC to 950oC and enhances conductivity. (ii) Al3+ + 3e- ----> Al. (iii) During electrolysis oxygen gas is formed at anode which oxidises graphite anode to carbon dioxide, so it is necessary to replace anode periodically. |
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