AL => AL CL => AL (OH)3=> AL2O3=>AL (SO4)3
2Al + 3Cl2 = 2AlCl3
AlCl3 + 3NaOH = Al(OH)3 + 3NaCl
2Al(OH)3 -> Al2O3 + 3H2O
Al2O3 + 3H2SO4 = Al2(SO4)3 +3 H2O