Electrolysis of aqueous NaCl: H₂, Cl₂ and NaOHजलीय NaCl का वैद्युत-अपघटन: H₂, Cl₂ और NaOHElectrolysis of aqueous NaCl: H₂, Cl₂ and NaOH

Class 12 Chemistry · Chapter 2 · interactive diagram

Parts and what they mean

• Cathode: water is reduced, not Na⁺ (कैथोड: Na⁺ नहीं, पानी अपचित होता है) — Na⁺ + e⁻ → Na has E° = −2.71 V; H⁺ + e⁻ → ½H₂ has 0.00 V. The higher E° wins, so: H₂O(l) + e⁻ → ½H₂(g) + OH⁻.
• Anode: Cl⁻ is oxidised (overpotential of O₂) (ऐनोड: Cl⁻ ऑक्सीकृत (O₂ का अतिविभव)) — By E° alone water (1.23 V) should be oxidised before Cl⁻ (1.36 V), but because of the overpotential of oxygen, Cl⁻ → ½Cl₂ + e⁻ is preferred.
• Hydrogen gas at the cathode (कैथोड पर हाइड्रोजन गैस) — OH⁻ left behind with Na⁺ gives NaOH in solution.
• Chlorine gas at the anode (ऐनोड पर क्लोरीन गैस) — Net: NaCl(aq) + H₂O(l) → Na⁺(aq) + OH⁻(aq) + ½H₂(g) + ½Cl₂(g).
• Aqueous NaCl (brine) (जलीय NaCl (लवण-जल)) — Molten NaCl gives Na metal and Cl₂ instead — there is no water to compete.
• DC source (DC स्रोत) — Supplies the energy to drive the non-spontaneous reaction.

Original diagram drawn by Simple Learning Hub, based on the NCERT textbook. Report a mistake