The enthalpy change for the reaction 2POCl3(s) + O2(g) ⟶ Fe2O3(s) + SO2(g) is ∆H° = 543 kJ for the reaction as written. (a) Is this reaction endothermic or exothermic? How do you know? (b) Given that the ∆Hf ° = −558.48 kJ/mol for POCl3, calculate ∆Hf ° for PCl3. (c) In a calorimetry experiment, what mass of POCl3 (153.32 g/mol) would give an enthalpy change of 155 kJ?​