Products of electrolysis depend on the nature of material being electrolyzed and the type of electrodes being used. If the electrode is inert (e.g., platinum or gold), it does not participate in the chemical reaction and acts only as source or sink for electrons. On the other hand, if the electrode is reactive, it participates in the electrode reaction. Thus, the products of electrolysis may be different for reactive and inert electrodes. The products of electrolysis depend on the different oxidizing and reducing species present in the electrolytic cell and their standard electrode potentials. Moreover, some of the electrochemical processes although feasible, are so slow kinetically that at lower voltages these do not seem to take place and extra potential (called overpotential) has to be applied, which makes such process more difficult to occur.

NaCl solution using Hg as cathode and graphite rod as anode is electrolysed. What are the products of electrolysis at anode and cathode respectively?

Cl₂ & Na

NaCl solution using Hg as cathode and graphite rod as anode

NaCl ⇌ Na⁺ + Cl^-

H₂O ⇌ H⁺ + OH^-

At anode: 2Cl^- → Cl₂ + 2e^-

At cathode: 2Na⁺ + 2e^- → 2Na

The discharge potential of Na⁺ is less than H⁺ towards mercury. Hence, Na⁺ discharges at cathode.