Chemistry
Observe the diagram given below used in the electrolysis of aqueous CuSO4 solution. Study the diagram and answer the following.
(a) Write the equation for the reactions that is occurring at anode and cathode.
(b) State two appropriate observations for the given electrolysis reaction.
(c) Why does the blue colour of Cu2+ ions in the electrolytic solution fades slowly? Explain.
Electrolysis
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Answer
(a) Reaction at cathode:
Cu2+ + 2e- ⟶ Cu
Reaction at anode:
OH1- - 1e- ⟶ OH x 4
4OH ⟶ 2H2O + O2
(b) Two observations for this electrolysis are:
- Pink or reddish brown copper is deposited at the cathode.
- The blue colour of copper sulphate solution slowly fades away and it becomes colourless.
(c) As the Cu2+ ions are discharged at the cathode and deposited as copper metal, there is a decrease in Cu2+ ions in the solution. This causes the blue colour to fade slowly and finally the solution becomes colourless as soon as Cu2+ ions are finished.
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