Al⇒Al2O3⇒AlCl3⇒Al(OH)3⇒Al2(SO4)3

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1) 4Al + 3O₂ = 2Al₂O₃.2) Al₂O₃ + 6HCl = 2AlCl₃ + 3H₂O.3) AlCl₃ + 3NaOH = 3NaCl + Al(OH)₃.4) 2Al(OH)₃ + 3H₂SO₄ = Al₂(SO₄)₃ + 6H₂O.