The vapoure pressure of benzene and toluene at `20^(circ)C` are `75 mm` of `Hg` and `22mm` of `Hg` respectively. `23.4g` of benzene and `64.4g` of toluene are mixed. If two forms ideal solution, calculate the mole fraction of benzene in vapour phase when vapour are in equilibrium with liquid mixture.

Explanation

Calculation of the total vapour pessure
`"Moles of benzene "(n_(B))=("Mass of" CH_(3)COOC_(2)H_(5))/("Molar massof benzene")(C_(6)H_(6))=((23.4g))/((78g mol^(-1)))=0.3` mol
`" Mole fraction of benzene"(x_(A))=("Mass of toluene")/("Molar mass jof toluene"(C_(7)H_(8)))= ((64.4g))/((92g mol^(-1)))=0.7` mol
`"Mole faction of benzene"(x_(B))=n_(B)/(n_(a)+n_(B))=((0.3mol))/((0.3mol+0.7 mol))=0.3`
`"mole fraction of toluene "(x_(A))=n_(A)/(n_(A)+n_(B))/((0.7 mol))/((0.3 mol+0.7mol))=0.7 `
`"Mole fraction of toluene"((x_(A))=n_(A)/((0.3mol+0.7mol))=0.7`
`" Vopour pressre of benzene in soulution "(P_(B))=P_(B)^(@)xxx_(B)=(67mm)xx0.3=22.5mm`
Calculoation of mnole fractin of benxene in the vapur phase.
`"Mole fration of benzene in vapur phase"=("Partial lllvapour prassure of benzene")/("Total vapour pressure")`
`((22.5mm))/((37.9mm))=0.59`.