Question

When copper sulfate solution is electrolyzed with copper electrodes, the blue copper ions are discharged at the cathode and get deposited as copper, yet the blue color of the solution does not fade.Explain.

Answer 1

When copper sulphate solution is electrolyzed with copper electrodes, the blue copper ions are discharged at the cathode and get deposited as copper, yet the blue colour of the solution does not fade. Because:

• For every copper ion ${\mathrm{Cu}}^{+2}$ discharged at the cathode as the neutral copper atom$\mathrm{Cu}$, a copper ion ${\mathrm{Cu}}^{+2}$ is released or added to the solution at the anode and hence the total number of ${\mathrm{Cu}}^{+2}$ ions remains the same. Therefore the blue colour of ${\mathrm{CuSO}}_4$does not fade in electrolytic reaction.
• The blue colour of aqueous copper sulphate does not fade because of the copper electrodes used as cathode and anode. if the platinum electrode is used, the colour will fade.