Al2O3-Al2(SO4)2-Al(OH)3-Al2o3
Al₂O₃+3H₂SO₄=Al₂(SO₄)₃+3H₂O Al₂(SO₄)₃+6NaOH=2Al(OH)₃ (осадок)+3Na₂SO₄ 2Al(OH)₃=(t)Al₂O₃+3H₂O