Neco Model Questions Vol1 2024 Chemistry Question 20

Chlorine (Cl) and bromine (Br) each form interhalogen compounds with fluorine: ClF₃ and BrF₃. The bond dissociation energy for a Cl-F bond is 250 kJ mol⁻¹, and for a Br-F bond is 230 kJ mol⁻¹. Each molecule contains three identical X-F bonds. Assume that the standard enthalpy of formation of each interhalogen from its elements equals the sum of the energies of the three bonds (energy released, taken as negative). The standard enthalpies of formation of Cl₂(g), Br₂(g) and F₂(g) are zero.\n\nConsider the overall reaction: \(2\,Cl_{2} + 2\,Br_{2} + 6\,F_{2} \rightarrow 2\,ClF_{3} + 2\,BrF_{3}\).\n\n(a) Calculate the standard enthalpy change (ΔH°) for this reaction.\n(b) Based on the calculated ΔH°, state which interhalogen, ClF₃ or BrF₃, is thermodynamically more stable per mole of compound formed.