$a,3Fe+2Cl_2\xrightarrow{t^o}2FeCl_3\\ FeCl_3+NaOH\to Fe(OH)_3\downarrow+3NaCl\\ 2Fe(OH)_3\xrightarrow{t^o}Fe_2O_3+3H_2O\\ Fe_2O_3+3H_2SO_4\to Fe_2(SO_4)_3+3H_2O\\ Fe_2(SO_4)_3+3BaCl_2\to 3BaSO_4\downarrow+2FeCl_3$

$b,Fe+2HCl\to FeCl_2+H_2\\ FeCl_2+2AgNO_3\to 2AgCl\downarrow+Fe(NO_3)_2\\ Fe(NO_3)_2+2NaOH\to Fe(OH)_2\downarrow+2NaNO_3\\ Fe(OH)_2\xrightarrow{t^o}FeO+H_2O\\ FeO+H_2SO_4\to FeSO_4+H_2O$

$c,2Cu+O_2\xrightarrow{t^o}2CuO\\ CuO+2HCl\to CuCl_2+H_2\\ CuCl_2+2NaOH\to Cu(OH)_2\downarrow+2NaCl\\ Cu(OH)_2\xrightarrow{t^o}CuO+H_2O\\ CuO+H_2\xrightarrow{t^o}Cu+H_2O\\ Cu+2H_2SO_4\to CuSO_4+2H_2O+SO_2\uparrow$

$d,2Al_2O_3\xrightarrow[criolit]{đpnc}4Al+3O_2\\ 2Al+6HCl\to 2AlCl_3+3H_2\\ AlCl_3+3NaOH\to Al(OH)_3\downarrow+3NaCl\\ 2NaCl+2H_2O\xrightarrow[cmn]{đpdd}2NaOH+Cl_2\uparrow+H_2\uparrow\\ 2NaOH+CuCl_2\to Cu(OH)_2\downarrow+2NaCl$

a/

2Fe + 3Cl2 ->to 2FeCl3

FeCl3 + 3NaOH -> Fe(OH)3 + 3NaCl

2Fe(OH)3 -> to Fe2O3 + 3H2O

Fe2O3 + 3H2SO4 -> Fe2(SO4)3 + 3H2O

Fe2(SO4)3 + 3BaCl2 -> 3BaSO4 + 2FeCl3

b/

Fe + 2HCl -> FeCl2 + H2

FeCl2 + 2AgNO3 -> 2AgCl + Fe(NO3)2

Fe(NO3)2 + 2NaOH -> Fe(OH)2 + 2NaNO3

Fe(OH)2 -> to ( không có O2 ) FeO + H2O

FeO + H2SO4 -> FeSO4 + H2O

c/

2Cu + O2 -> to 2CuO

CuO + 2HCl -> CuCl2 + H2O

CuCl2 + 2NaOH -> Cu(OH)2 + 2NaCl

Cu(OH)2 -> to CuO + H2O

CuO + H2 -> to Cu + H2O

Cu + 2H2SO4(đặc) -> to CuSO4 + 2H2O + SO2

d/ 2Al2O3 -> đpnc ( criôlit Na3AlF6 ) 4Al + 3O2

2Al + 6HCl -> 2AlCl3 + 3H2

AlCl3 + 3NaOH ( vừa đủ ) -> Al(OH)3 +  3NaCl

2NaCl + 2H2O -> đpdd có màng ngăn 2NaOH + H2 + Cl2

2NaOH + CuCl2 -> Cu(OH)2 + 2NaCl