4)Al-Al2O3-AlCl3-Al(OH)3-Al2(SO4)3
Al-Al₂O₃-AlCl₃-Al(OH)₃-Al₂(SO4)₃
4Al + 3O₂ = 2Al₂O₃
Al₂O₃ + 6HCI = 2AlCl₃ + 3H₂O
AlCl₃ + 3NaOH = Al(OH)₃↓ + 3NaCI
2Al(OH)₃ + 3H₂SO₄ = Al₂(SO4)₃ + 6H₂O