Q4.Calculate the enthalpy change for the reaction H₂(g) + Cl₂(g) → 2HCl(g), given the average bond enthalpies: H-H bond energy = 436 kJ mol⁻¹ Cl-Cl bond energy = 242 kJ mol⁻¹ H-Cl bond energy = 431 kJ mol⁻¹