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In the extraction of Aluminium by electrolysis. (i) Write overall cell reaction.(ii) What is the role of cryolite? |
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Answer» i) At cathode - Al+3 (melt) + 3e- → Al(l) At anode - C(s) + O2- (melt) → Co(g) + 2e- C(s) + 2O2- (melt) → CO2 (g) + 4e- ii) Cryolite (Na3Al F6) makes Alumina good conductor of electricity and lowers the melting (fusion) + temperature of Alumina. (i) 2Al2O3 + 3C → 4Al + 3CO2 Al2O3 \(\overset{electrolysis}{\longrightarrow}\) 2Al3 + 3O2- (ii) Cryolite lowers the melting point of the mixture and increases the conductivity. |
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