Note : In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
Assertion : Electrolysis of NaCl solution gives chlorine at anode instead of O2.
Reason : Formation of oxygen at anode requires overvoltage.
In the electrolysis of NaCl solution, Chlorine is produced at anode instead of O2. The two half-cell reactions are:
2Cl-→ Cl2(g) + 2e- E° = -1.36V
2H2O →O2(g) + 4H+ + 4e- E° = -1.23V
Generally, the one with the lower value is preferred but in this case Chlorine is produced at anode. This is because formation of oxygen at anode requires overvoltage.