The heat of hydration for the reaction can be calculated by dividing the enthalpy change of the reaction by the number of moles of water involved in the reaction.Enthalpy change of the reaction = -65 kJ/molNumber of moles of water = 5 molHeat of hydration = Enthalpy change / Number of moles of waterHeat of hydration = -65 kJ/mol / 5 molHeat of hydration = -13 kJ/mol per mole of water