Write the balanced chemical equation for the reaction of zinc with sodium hydroxide solution.
Generated by claude-sonnet-4-6 · 2026-06-17 12:33 · grounding rag
Model Answer
When zinc reacts with sodium hydroxide solution, it produces sodium zincate and hydrogen gas. The balanced chemical equation is:
$$\text{Zn}(s) + 2\text{NaOH}(aq) \rightarrow \text{Na}_2\text{ZnO}_2(aq) + \text{H}_2(g)$$
Zinc displaces hydrogen from sodium hydroxide, forming sodium zincate (Na₂ZnO₂) and hydrogen gas. This shows zinc is amphoteric — it reacts with both acids and bases.
Explanation
- The examiner expects the correctly balanced equation (1 mark) and state symbols or identification of products (1 mark).
- Key point: Zinc is amphoteric; it reacts with NaOH (a base) just as it reacts with dilute acids, releasing H₂ gas both times.
- Products to remember: sodium zincate (Na₂ZnO₂) and hydrogen gas (H₂) — students often forget the zincate formula.
- Coefficients: 2 NaOH is needed to balance Na and H on both sides.