At a given temperature the vapour pressures of benzene and toluene are 183 mmHg and 59.2 mmHg, respectively. Calculate the total vapour pressure over a solution of benzene and toluene with X_benzene = 0. 580. A) 106 mmHg B) 121 mmHg C) 131 mmHg D) 242 mmHg

Question

Quizplus · Accepted Answer

Total vapour pressure over the solution can be calculated using Raoult's law: Total vapour pressure = Pbenzene + Ptoulene where Pbenzene is the vapour pressure of pure benzene and Ptoulene is the vapour pressure of pure toluene. According to Raoult's law, the vapour pressure of a component in the solution is equal to the product of its mole fraction and the vapour pressure of the pure component. Therefore, we can write: Pbenzene = X_benzene × P°benzene Ptoulene = (1 - X_benzene) × P°toluene where P°benzene and P°toluene are the vapour pressures of pure benzene and toluene, respectively. Substituting the values given in the question, we get: Pbenzene = 0.580 × 183 mmHg = 106.14 mmHg Ptoulene = (1 - 0.580) × 59.2 mmHg = 24.86 mmHg Therefore, the total vapour pressure over the solution is: Total vapour pressure = Pbenzene + Ptoulene = 106.14 mmHg + 24.86 mmHg = 131 mmHg Hence, the correct answer is C.

At a Given Temperature the Vapour Pressures of Benzene and Toluene