Al + Cl₂ → AlCl₃
2Al + 3Cl₂ → 2AlCl₃
CO + O₂ → CO₂
2CO + O₂ → 2CO₂
MnO₂ + Al → Al₂O₃ + Mn
3MnO₂ + 4Al → 2Al₂O₃ + 3Mn
H₂S + O₂ → S + H₂O
2H₂S + 3O₂ → 2S + 2H₂O