Question

The metals produced by various reduction processes are not very pure. They contain impurities, which must be removed to obtain pure metals. The most widely used method for refining impure metals is electrolytic refining.
(i) What is the cathode and anode made of in the refining of copper by this process?
(ii) Name the solution used in the above process and write its formula.
(iii) (A) How copper gets refined when electric current is passed in the electrolytic cell?
OR
(iii) (B) You have two beakers ‘A’ and ‘B’ containing copper sulphate solution. What would you observe after about 2 hours if you dip a strip of zinc in beaker ‘A’ and a strip of silver in beaker ‘B’? Give reason for your observations in each case.

Answer 1

(i). - Cathode: Pure copper plate.
    - Anode: Impure copper block.
(ii).- Solution: Acidified copper sulphate solution.
      - Formula: \( CuSO_4\)
(iii)A - When current is passed, copper ions (Cu²⁺) from the solution are reduced at the cathode, depositing pure copper.
          - At the anode, impure copper oxidizes, releasing Cu²⁺ ions into the solution. Impurities settle as anode mud.
(iii)B • Beaker ’A’ (Zinc strip): The zinc strip gets coated with copper, and the blue color of CuSO4 fades.
            Reason: Zinc is more reactive than copper and displaces Cu²⁺ ions from the solution.
         • Beaker ’B’ (Silver strip): No change is observed.
            Reason: Silver is less reactive than copper and cannot displace Cu²⁺ ions from the  solution.