Write the balanced chemical equation for the chlor-alkali process. Name the electrode at which (i) chlorine is produced and (ii) hydrogen is produced. State one industrial use of the sodium hydroxide produced.
Generated by claude-sonnet-4-6 · 2026-06-26 01:04 · grounding rag
Model Answer
Balanced chemical equation for the chlor-alkali process:
$$2\text{NaCl(aq)} + 2\text{H}_2\text{O(l)} \xrightarrow{\text{electricity}} 2\text{NaOH(aq)} + \text{Cl}_2\text{(g)} + \text{H}_2\text{(g)}$$
(i) Chlorine is produced at the anode (positive electrode).
(ii) Hydrogen is produced at the cathode (negative electrode).
Industrial use of NaOH: Sodium hydroxide is used in the manufacture of soaps and detergents (also used in paper making and de-greasing metals).
---
Explanation
- The equation must be balanced and include state symbols — examiners check this.
- "Chlor-alkali" refers to the electrolysis of brine (NaCl solution) producing chlorine (Cl₂), alkali (NaOH), and hydrogen (H₂) — remember all three products.
- Anode = oxidation → Cl⁻ loses electrons → Cl₂ formed. Cathode = reduction → H⁺ gains electrons → H₂ formed. This anode/cathode distinction is a common 1-mark trap.
- Any one valid industrial use of NaOH earns the mark (soaps, paper, textiles, de-greasing).