Answer to Question #327741 in General Chemistry for qt ku

Question

The vapor pressures of pure toluene and pure benzene at 25°C are 13.5 and 95.2 mmHg, respectively. A solution is prepared in which the mole fractions of toluene and benzene are 0.4 and 0.6, respectively. What are the partial pressures of the benzene and toluene above this solution? What is the total pressure of the solution?

Answer 1

x(toluene) = 0.4 = 40 %;

x(benzene) = 0.6 = 60 %;

P₀(toluene) = 13.5 mmHg;

P₀(benzene) = 95.2 mmHg;

P_toluene = x(toluene) * P₀(toluene) = 0.4 * 13.5 = 5.4 mmHg;

P_benzene = x(benzene) * P₀(benzene) = 0.6 * 95.2 = 57.1 mmHg;

P_solution = P_toluene + P_benzene;

P_solution = x(toluene) * P₀(toluene) + x(benzene) * P₀(benzene) = 0.4 * 13.5 + 0.6 * 95.2 = 5.4 + 57.1 = 65.5 mm Hg.