The vapour pressure of pure benzene and toluene are 160 and 60 torr respctively. The mole fraction of touene in vapour phase in contact with equimolar solution of benzene and toluene is

Options

A. 0.5
B. 0.6
C. 0.27
D. 0.73

Answer

C

Explanation

For equimolar solutions, `X_(B) = X_(T) = 0.5`
`P_(B) = X_(B) xx P_(B)^(o)=0.5 xx 160=80 mm`
`P_(T) = X_(T) xx P_(T)^(o)=0.5 xx 60 =30 mm`
`P_("Total")=80+30=110 mm`
Mole fraction of toluene in vapour phase =30/110=0.27