Question

At 25°c, the vapor in equilibrium with a solution containing carbon disulfide and acetonitrile has a total pressure of 250. torr and is 85.7 mole percent carbon disulfide. what is the mole fraction of carbon disulfide in the solution? at 25°c the vapor pressure of carbon disulfide is 361 torr. assume that the solution and vapor exhibit ideal behavior.

Answer 1

For this question, we apply the Raoult's Law. The formula is written below:

P = P*x
where
P is the partial pressure
P* is the vapor pressure of the pure solvent
x is the mole fraction

The partial pressure is solved as follows:
P = Total P*x = (250 torr)(0.857) = 214.25 torr
Hence,
214.25 = (361 torr)(x)
x = 0.593 or 59.3%