In this method, the impure metal is made to act as anode. A strip of the same metal in pure form is used as cathode. They are put in a suitable electrolytic bath containing soluble salt of the same metal. The more basic metal remains in the solution and the less basic ones go to the anode mud. This process is also explained using the concept of electrode potential, over potential, and Gibbs energy which you have seen in previous sections. The reactions are:
Copper is refined using an electrolytic method. Anodes are of impure copper and pure copper strips are taken as cathode. The electrolyte is acidified solution of copper sulphate and the net result of electrolysis is the transfer of copper in pure form from the anode to the cathode:
Impurities from the blister copper deposit as anode mud which contains antimony, selenium, tellurium, silver, gold and platinum; recovery of these elements may meet the cost of refining. Zinc may also be refined this way.
Exam | Chapter |
MHT-CET | General principles and processes of isolation of elements |
When the sample of copper with zinc impurity is to be purified by electrolysis, the appropriate electrodes are
Cathode | Anode |
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(a) Pure Zinc | Pure Copper |
(b) Impure Sample | Pure Copper |
(c) Impure Zinc | Impure Sample |
(d) Pure Copper | Impure Sample |
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Aluminium is extracted by the electrolysis of
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During the process of electrolytic refining of copper, some metals present as impurity settle as ' anode mud ' These are
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The electrolytes usually used in the electroplating of gold and silver respectively are:
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