In the electrolysis of alumina, a layer of powdered coke is spread on the surface of the electrolyte in the cell

Question

In the electrolysis of alumina, a layer of powdered coke is spread on the surface of the electrolyte in the cell (A) to decrease the melting point of alumina (B) to increase the electrical conductivity (C) to prevent the heat lost by radiation and oxidation of carbon electrode (D) none of the above

Tardigrade Admin · Accepted Answer

In the electrolysis of fused alumina, cryolite and fluorspar, oxygen is liberated at the anode reacts with carbon anode to form CO. The hot CO comes in contact with air and burn spontaneously giving CO2. Consequently, the anodes get corroded and have to be replaced from time to time. However, the layer of powdered coke spread at the surface of molten electrolyte slows down the consumption of the anode and prevent heat loss due to radiation

Q. In the electrolysis of alumina, a layer of powdered coke is spread on the surface of the electrolyte in the cell

to decrease the melting point of alumina

to increase the electrical conductivity

to prevent the heat lost by radiation and oxidation of carbon electrode

none of the above