Molten NaCl is electrolyzed with inert electrodes. Given E°(Na⁺/Na) = −2.71 V and E°(Cl₂/Cl⁻) = +1.36 V, what minimum applied voltage lets the process run?

Core Concept

The forced overall reaction is 2 Na⁺ + 2 Cl⁻ → 2 Na(l) + Cl₂(g), whose standard potential is E°cathode − E°anode = (−2.71) − (+1.36) = −4.07 V. That strongly negative value confirms the process is nonspontaneous as written. An external supply must apply at least +4.07 V to cancel the deficit; anything less leaves ΔG positive and no sustained current flows.