Vapour pressure of pure benzene is and toluene is at the same temperature. Mole fraction of toluene in vapour phase which is in equilibrium with a solution of benzene and toluene having a mole fraction of toluene, will be:
Step 1: Calculation of Total pressure
The total pressure is given by
Where Total pressure , are the mole fraction of Toluene and Benzene in equilibrium respectively and are the vapor pressure of Toluene and Benzene respectively
Step 2: Calculating Mole fraction of toluene in a vapor phase
Mole fraction in the vapor phase is given by
Where is the mole fraction of toluene in a vapor phase
Therefore, the Mole fraction of toluene in the vapor phase is .