Write a balanced equation for the reaction of phosphorus trichloride, PCl3, with water, H2O, forming phosphorous acid, H3PO3 and hydrochloric acid, HCl. Calculate the heat of reaction from the standard heats of formation listed below. Then, calculate the standard enthalpy change when 36.8 grams of water is consumed in this reaction. standard heat of formation(PCl3) -287 kJ/mol standard heat of formation(H2O) -285 kJ/mol standard heat of formation(H3PO3) -972 kJ/mol standard heat of formation(HCl) -167 kJ/mol.