a,
- PT phân tử: $CaCO_3+2HCl\to CaCl_2+CO_2+H_2O$
- PT ion: $CaCO_3+2H^++2Cl^-\to Ca^{2+}+2Cl^-+CO_2+H_2O$
b,
- PT phân tử: $Na_2SO_4+BaCl_2\to BaSO_4+2NaCl$
- PT ion: $2Na^++SO_4^{2-}+Ba^{2+}+2Cl^-\to BaSO_4+2Na^++2Cl^-$
c,
- PT phân tử: $3NaOH+FeCl_3\to Fe(OH)_3+3NaCl$
- PT ion: $3Na^++3OH^-+Fe^{3+}+3Cl^-\to Fe(OH)_3+3Na^++3Cl^-$