Q1. [2] medium exam-ready
Magnesium does not react with cold water but reacts with hot water and also with steam. What products are formed in each case? Write the equation for the reaction of magnesium with steam.
Generated by claude-sonnet-4-6 · 2026-06-26 01:05 · grounding rag
Model Answer
- With hot water: Magnesium reacts to form magnesium hydroxide and hydrogen gas.
- With steam: Magnesium reacts to form magnesium oxide and hydrogen gas.
Equation for reaction with steam:
$$\text{Mg(s)} + \text{H}_2\text{O(g)} \rightarrow \text{MgO(s)} + \text{H}_2\text{(g)}$$
Source: Chapter 3, Section 3.2.2
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Explanation
- The key distinction: hot water → Mg(OH)₂ (hydroxide); steam → MgO (oxide). This difference is commonly tested.
- Examiners expect both products named for each case and the balanced chemical equation for steam specifically.
- Remember: Mg does not react with cold water at all — state this if asked.