A vessel initially containing propane at 5275 R is connected

A vessel initially containing propane at 527.5 R is connected to a nitrogen cylinder, and the pressure is increased to 248 psia. Assuming that the nitrogen is insoluble in liquid propane, what is the mol fraction of propane in the vapor phase? List all assumptions. The vapor pressure of propane at 527.5 R is 125 psia.

Solution

Assumptions

1) Gases do not react.

2) Both Gases are considered to be ideal.

3) Intermolecular forces between unlike molecules are equal to those between similar molecules.

Then according to Raoults Law

Mole fraction of propane = vapor pressure of propane / total pressure

                                     = 125 / 248   = 0.50403