At a given temperature, you have a mixture of benzene (vapor pressure of pure benzene = 745 torr) and toluene (vapor pressure of

Question

20 days ago

14

At a given temperature, you have a mixture of benzene (vapor pressure of pure benzene = 745 torr) and toluene (vapor pressure of

pure toluene = 290 torr). The mole fraction of benzene in the vapor above the solution is 0.590. Assuming ideal behavior, calculate the mole fraction of toluene in the solution.

Chemistry

1 answer:

castortr0y [3K] · Answer 1 · 2026-04-01T16:06:06+03:00

Ideal solutions adhere to Raoult's law, articulated as:

P_i = x_i*(P_pure)_i

where
P_i represents the partial pressure of component i above a solution
x_i denotes the mole fraction of component i within the solution
(P_pure)_i signifies the vapor pressure of pure component i

In this scenario,

P_benzene = 0.59 * 745 torr = 439.6 torr
P_toluene = (1-0.59) * 290 torr = 118.9 torr

To compute the total vapor pressure above the solution, sum the individual vapor pressures of the components:

P_total = (439.6 + 118.9) torr = 558.5 torr

Assuming ideal behavior in the gaseous phase, the partial pressure of each gas corresponds to its molar concentration; thus, the mole fraction of toluene in the vapor phase is:

118.9 torr/558.5 torr = 0.213