Question

Observe the figure and answer the following.

1. Write the name of the method.
2. What is used as anode and cathode in this method?
3. Write the molecular formula and use of cryolite.
4. Write anode reaction.
5. Write cathode reaction.

Answer 1

1. The method shown is an electrolytic reduction of alumina.
2. A set of graphite rods dipped in the molten electrolyte acts as the anode. and the graphite lining acts as a cathode.
3. Molecular formula of cryolite: Na₃AlF₆
   Use of cryolite: Addition of cryolite reduces the melting point of alumina to about 1000 °C.
4. Anode reaction: \[\ce{2O^2+ -> O2 + 4e^-}\]
5. Cathode reaction: \[\ce{Al^3+ + 3e^- -> Al_{(l)}}\]