A solution is made of 184 g toluene (C 7H 8, 92 g/mol) and 234 g benzene (C 6H 6, 78g/mol). At 20 degrees C, the vapor pressure of pure toluene is 22 torr and the vapor pressure of pure benzene is 75 torr. What is the pressure of toluene above the solution at 20 degrees C?

Answer : The pressure of toluene is, 8.8 torr

Explanation : Given,

Vapor pressure of pure toluene = 22 torr

Vapor pressure of pure benzene = 75 torr

First we have to calculate the mole fraction of toluene and benzene.

and,

Now we have to calculate the mole fraction of toluene and benzene.

and,

Now we have to calculate the pressure of toluene.

where,

= pressure of toluene = ?

= vapor pressure of pure toluene = 22  torr

= mole fraction of toluene = 0.4

Thus, the pressure of toluene is, 8.8 torr