mg+O2-MgO

Balanced chemical equation:

• Unbalanced: Mg + O2 → MgO
• Balanced: 2 Mg + O2 → 2 MgO

Reason: O2 provides two oxygen atoms, while MgO contains one O per formula unit, so you need 2 MgO on the product side. Check: Mg atoms 2 on both sides; O atoms 2 on both sides.

State symbols (optional): Mg(s) + O2(g) → MgO(s)

Quick practice (optional):

• If 5.0 g Mg reacts with excess O2, how much MgO forms?
  • Molar masses: Mg ≈ 24.31 g/mol; MgO ≈ 40.31 g/mol
  • Moles Mg = 5.0 / 24.31 ≈ 0.206 mol
  • Moles MgO formed = 0.206 mol (stoichiometry 1:1 with Mg)
  • Mass MgO ≈ 0.206 × 40.31 ≈ 8.3 g

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