CaO + H2O = Ca(OH)2
Ca(OH)2 -> CaO + H2O
CaO + 2HCl = CaCl2+ H2O
CaCl2 + H2SO4 = CaSO4 + 2HCl
CaSO4 -> CaO + SO3
SO3 + H2O = H2SO4
H2SO4 + 2NaOH = Na2SO4 + 2H2O
Na2SO4 +Ba(OH)2 = BaSO4 + 2NaOH
NaOH + HNO3 = NaNO3 + H2O
