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).

(e) (2%) Initial partial pressures (before reaction) are 1.00 atm, and 1.00 atm for H₂(g) and D₂(g), respectively. Using the law of mass action based on the equilibrium constant K, calculate the partial pressure of each gas at equilibrium. [Note: You can reach the same result by using the total entropy of mixing as a function of the extent of reaction for these three components in the system. However, the implicit assumption on the molar entropy of reactants and product need to be made with this approach.]