Under what pressure must an equimolar mixture of Cl₂ and PCl₃ be place at 250°C in order to obtain 7 — Chemical Equilibrium Chemistry Question

💡 Solution & Explanation

Initial moles: 1 mol Cl₂, 1 mol PCl₃. Reacted: 0.75 mol each. Eq moles: Cl₂ = 0.25, PCl₃ = 0.25, PCl₅ = 0.75. Total eq moles = 1.25. P_Cl₂ = (0.25/1.25)P_eq = 0.2 P_eq, P_PCl₃ = 0.2 P_eq, P_PCl₅ = 0.6 P_eq. K_p = 0.6 P_eq / (0.2 P_eq × 0.2 P_eq) = 15 / P_eq = 2. So P_eq = 7.5 atm. Initial pressure P_init = P_eq × (Total initial moles / Total eq moles) = 7.5 × (2 / 1.25) = 12 atm. Therefore, correct answer is A.