а) Na → NaOH → Na₂CO₃ → NaCl → NaNO₃.
2Na + 2H₂O = 2NaOH + H₂↑.
2NaOH + H₂CO₃ = Na₂CO₃ + 2H₂O.
Na₂CO₃ + 2HCl = 2NaCl + CO₂↑ + H₂O.
NaCl + HNO₃ = NaNO₃ + HCl.
б) Ca → Ca(OH)₂ → CaCO₃ → CaO → CaCl₂.
Ca + 2H₂O = Ca(OH)₂↓ + H₂↑.
Ca(OH)₂ + H₂CO₃ = CaCO₃↓ + 2H₂O.
CaCO₃ t° → CaO + CO₂↑.
CaO + 2HCl = CaCl₂ + H₂O.
в) Al → AlCl₃ → Al(OH)₃ → Al₂O₃ → Al₂(SO₄)₃.
2Al + 6HCl = 2AlCl₃ + 3H₂↑.
AlCl₃ + 3KOH = 3KCl + Al(OH)₃↓.
2Al(OH)₃ t° → Al₂O₃ + 3H₂O.
Al₂O₃ + 3H₂SO₄ = Al₂(SO₄)₃ + 3H₂O.
г) C → CO₂ → Na₂CO₃ → CaCO₃ → Ca(NO₃)₂.
C + O₂ = CO₂↑.
CO₂ + 2NaOH = Na₂CO₃ + H₂O.
Na₂CO₃ + CaCl₂ = 2NaCl + CaCO₃↓.
CaCO₃ + 2HNO₃ = Ca(NO₃)₂ + CO₂↑ + H₂O.
д) P → P₂O₅ → H₃PO₄ → Na₃PO₄ → Ca₃(PO₄)₂.
4P + 5O₂ = 2P₂O₅.
P₂O₅ + 3H₂O = 2H₃PO₄.
H₃PO₄ + 3NaCl = Na₃PO₄ + 3HCl.
2Na₃PO₄ + 3Ca(NO₃)₂ = 6NaNO₃ + Ca₃(PO₄)₂↓.
е) S → SO₂ → Na₂SO₃ → H₂SO₃ → SO₂.
S + O₂ = SO₂.
SO₂ + 2NaOH = Na₂SO₃ + H₂O.
Na₂SO₃ + 2H₂O = 2NaОН + H₂SO₃.
H₂SO₃ → SO₂↑ + H₂O.
ж) Fe → FeCl₂ → Fe(OH)₂ → FeSO₄ → BaSO₄.
Fe + 2HCl = FeCl₂ + H₂↑.
FeCl₂ + 2KOH = Fe(OH)₂↓ + 2KCl.
Fe(OH)₂ + H₂SO₄ = FeSO₄ + 2H₂O.
FeSO₄ + Ba(NO₃)₂ = Fe(NO₃)₂ + BaSO₄↓.
з) Fe → FeCl₃ → Fe(OH)₃ → Fe₂O₃ → Fe₂(SO₄)₃.
2Fe + 3Cl₂ = 2FeCl₃.
FeCl₃ + 3NaOH = Fe(OH)₃↓ + 3NaCl.
2Fe(OH)₃ t° → Fe₂O₃ + 3H₂O.
Fe₂O₃ + 3H₂SO₄ = Fe₂(SO₄)₃ + 3H₂O.