Balance the following chemical equation:
Mg + O₂ → MgO
Write the balanced equation and state the ratio in which magnesium and oxygen combine.
Generated by claude-sonnet-4-6 · 2026-06-26 00:53 · grounding rag
Model Answer
Balanced equation:
$$2\text{Mg} + \text{O}_2 \rightarrow 2\text{MgO}$$
Verification: LHS — Mg: 2, O: 2 | RHS — Mg: 2, O: 2 ✓
Ratio of combination: Magnesium and oxygen combine in the ratio 2 : 1 (in terms of number of molecules/moles).
Source: Chapter 1, Section 1.1.2 Balanced Chemical Equations
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Explanation
- The skeletal equation Mg + O₂ → MgO is unbalanced (2 O on left, 1 O on right). Place coefficient 2 before both Mg and MgO to balance all atoms.
- Examiners award 1 mark for the correct balanced equation and 1 mark for stating the correct ratio (2 Mg : 1 O₂).
- Never change subscripts to balance; only add coefficients in front of formulae.