申論題

5. (20%) The two gases H₂(g) and D₂(g) (Deuterium molecule) are mixed in equal molar amounts. The mixture tends to react to form HD(g) (g) according to the isotope exchange reaction H₂(g) + D₂(g)⇌2HOD(g).

(f) (2%) In fact, the enthalpy change A.H° for this reaction is the difference in zero-point energy (ZPE=1/2 hv, where v is the vibrational frequency of the molecule) between products and reactants: △_rH°= ZPE(products) - ZPE(reactants). Using the following vibrational wavenumber (v) for H₂, D₂, and HD: 4390.cm^-¹, 3110 cm^-¹, and 3610 cm^-¹, respectively, calculate ZPE for each molecule, and △_rH°(in unit, J/mol). Is this reaction exothermic or endothermic