a,
2Al+ 3H2SO4 -> Al2(SO4)3+ 3H2
Al2(SO4)3+ 6NH3+ 6H2O-> 2Al(OH)3+ 3(NH4)2SO4
2Al(OH)3 (t*)-> Al2O3+ 3H2O
Al2O3+ 6HCl -> 2AlCl3+ 3H2O
b,
Fe+ 3/2Cl2 (t*)-> FeCl3
FeCl3+ 3NaOH -> Fe(OH)3+ 3NaCl
2Fe(OH)3 (t*)-> Fe2O3+ 3H2O
Fe2O3+ 6HCl -> 2FeCl3+ 3H2O
c,
CaCO3 (t*)-> CaO+ CO2
CaO+ H2O -> Ca(OH)2
Ca(OH)2+ 2HCl -> CaCl2+ 2H2O
CaCl2+ 2AgNO3 -> Ca(NO3)2+ 2AgCl