Chemistry - Liquid Solution Question with Solution | TestHub

Mole fraction of toluene vapour$=\frac{{\mathrm{p}}_{\mathrm{T}}^{\mathrm{o}}{\mathrm{X}}_{\mathrm{T}}}{{\mathrm{P}}_{\mathrm{T}}^{\mathrm{o}}{\mathrm{X}}_{\mathrm{T}}+{\mathrm{p}}_{\mathrm{B}}^{\mathrm{o}}{\mathrm{X}}_{\mathrm{B}}}$

${\mathrm{X}}_{\mathrm{T}}=$Mole fraction of toluene in solution =2/4 = 0.5

${\mathrm{X}}_{\mathrm{B}}=$Mole fraction of benzene = 2/4 = 0.5

${\mathrm{p}}_{\mathrm{T}}^{\mathrm{o}}=$Vapour pressure of pure toluene = 80 mm

${\mathrm{p}}_{\mathrm{T}}^{\mathrm{o}}=$Vapour pressure of benzene = 120 mm

$=\frac{80\times 4}{5.80+120\times 0.5}=0.40$