1.Cu-->CuCL2-->NaCL-->NaNO3-->BaNO3-->BaNO2
2. CaCO3-->CaO-->H2SO4-->Na2SO4-->NaF-->Na
3. Mg-->MgO--> Mg(ClO4)2-->MgCL2-->Mg(OH)2--->MgO
4. Na-->Na2O-->NaOH-->Na2O
6HCl+2Al=2AlCl3+3H2
6HCl+Al2O3=2AlCl3+3H2O
6HCl+2Al(OH)3=2AlCl3+6H2O
2HCl+Ba(OH)2=BaCl2+2H2O
2KOH+ H2SO4= K2SO4+ 2H2O
3NaOH+H3PO4= Na3PO4 + 3H2O
LiOH+ HNO3= LiNO3+ H2O