Question

With reference to electrolytic reduction of alumina, answer the following:

i) Which material is cathode made up of?

ii) What is the composition of electrolyte?

iii) Why is powdered coke sprinkled over the surface of the electrolytic mixture?

iv) Why are the anodes replaced periodically?

v) Write the ionic equation for the reaction taking place at the anode.

Answer 1

Answer:

1) Cathode are made from plates of-porous nickel that start with a porosity of 70- 80%

2) CuC1²

SnC1²

ZnC1²

3) Powder coke is sprinkled over the surface of the electrolytic mixture:

Reduces heat loss of radiation.Prevents burning of the anode

4) Anodes needs to be replaced during the electrolysis of the Alumina because they gets oxidized

5) Pb( s) + SO4²- ( aq) -- PbSO 4( s )+2e-

Hope it helps

Answer 2

Explanation:

i) cathodes are made from plates of porous nickel that start with a porosity of 70–80%.

ii) the primary ions of electrolytes are sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), chloride (Cl−), hydrogen phosphate (HPO42−), and hydrogen carbonate (HCO3−).

iii) Powdered coke is sprinkled over the surface of the electrolytic mixture: Reduces heat loss by radiation. Prevents burning of the anode.

iv) During electrolysis, the metal at anode gets deposited on the cathode. Since it is gradually decreasing and gets deposited, a time comes when there is no flow of electricity as the anode is completely deposited on cathode. So for the process to continue the anode is replaced periodically.

v) Anode reaction : 2OH- −2e− → 2OH → H2O + O + O → O2