Question

Distinguish between electrolytic methods of reduction and refining.

Answer 1

Hint: In both the techniques electrolytic reduction and electrolytic refining metals are obtained by the electrolysis process. In electrolytic reduction, reduction reaction takes place and in electrolytic refining impurities are removed from the metal which are obtained from the electrolytic reduction.

Complete answer:
Electrolytic reduction: The reactive metals which are present above in the reactivity series are formed by the process of electrolytic reduction of their fused oxides or chlorides. During the electrolysis process, the cathode electrode donates the electrons to the metal ions to undergo reduction to generate metal. In this process the oxygen atom or the chloride atom is removed from the metal.
Example: Sodium metal generated from the electrolysis process by molten sodium chloride.
Electrolytic refining: The electrolytic refining is a technique used to refine the metals by the process of electrolysis. In this process a large impure metal is used as the anode and a thin slit of pure metal is used as the cathode dipped in the electrolyte which generally depends on the metal. As the current passes through the impure metal at anode, it starts dissolving and pure metal is obtained at the cathode. Electrolytic refining is also known as electrorefining.
Example: Electrolytic refining of copper metal containing impurities.

Note:
During the electrolytic reduction process of molten salts, the metal is always discharged on the cathode electrode. The oxides of higher metal only undergo electrolytic reduction because metal oxides have higher affinity for the oxygen atom as compared to the carbon atom and thus cannot be reduced by carbon monoxide, carbon or hydrogen.