1)4Al+3O2=2Al2O3
2)Al2O3+3H2SO4=Al2(SO4)3+3H2O
3)Al2(SO4)3+6KOH=3K2SO4+2Al(OH)3
4)2Al(OH)3=(t)Al2O3+3H2O
5)Al2O3+6HCl=2AlCl3+3H2O