Answer:
Mole fraction of benzene in pure solution is 0.4472
Explanation:
Vapor pressure of pure benzene= 750 torr
Vapor pressure of pure toulene= 300 torr
Mole fraction of benzene in vapor= 0.669
1/P=Xa/Pa+ Xb/Pb
Where
Xa = mole fraction of A in water
Xb = mole fraction of B in water
P= Total pressure
Pa= total vapor pressure of pure A
Pb = total vapor pressure of pure B
Xa+Xb=1
Let A be benzene and B be toulene
We have Xa=0.669 and Xb= 0.331
1/P= 0.669/750 + 0.331/300
1/P= 0.000892/torr + 0.001103/torr
1/P=0.001995/torr
P= 501.25torr
We have P= Pa+ Pb
Where Pa= XaPa0
And Pb=XbPb0
Where
Xa= mole fraction of A in solution
Xb= mole fraction of B in solution
Now, substitute the data into the formula
501.25torr=Xa750torr + (1- Xa) 300 torr
Xa450torr + 300torr
Xa(450torr)= 201.25torr
Xa= 0.4472
Therefore, mole fraction of benzene in pure solution is 0.4472
