Question

Select the correct answer from the list in the bracket:

The ions which is / are discharged during electrolysis of aq. ${\mathrm{CuSO}}_4$ solution using platinum electrodes. $\left({\mathrm{Cu}}^{2+},{\mathrm{SO}}_4^{2-},{\mathrm{H}}^{+}\right.$$,O{H}^{-})$

Answer 1

• Electrolysis is a process of passing an electric current into an electrolyte so as to produce some chemical changes in the solution of an electrolyte.
• When copper sulphate is dissolved in water, it dissociate into ${\mathrm{Cu}}^{2+}\mathrm{and}{{\mathrm{SO}}_4}^{2-}$ ions.
• Also pure water dissociates into ${\mathrm{H}}^{+}\mathrm{and}{\mathrm{OH}}^{-}$ ions.
• Platinum electrodes are inert electrodes i.e. they does not participate in chemical reaction taking place in electrolytic cell.
• At cathode, reduction of cations takes place.
• Here , there are two cations $({\mathrm{Cu}}^{2+}\mathrm{and}{\mathrm{H}}^{+}\mathrm{ions})$ but the reduction of ${\mathrm{Cu}}^{2+}$ion will take place due to its high reduction tendency
• At anode , oxidation of anion will take place.
• Here, there are two anions $({{\mathrm{SO}}_4}^{2-}\mathrm{and}{\mathrm{OH}}^{-}\mathrm{ions})$ but oxidation of ${\mathrm{OH}}^{-}$ ion takes place due to its high oxidation tendency and high stability of sulphate ion.
• Thus, The ions which is / are discharged during electrolysis of aq. ${\mathrm{CuSO}}_4$ solution using platinum electrodes are ${\mathrm{Cu}}^{2+}$ and ${\mathrm{OH}}^{-}$.