Benzene and toluene form nearly ideal solution. At a certain temperature the vapour pressure of pure benzene and toluene are 150 and 50 torr. respectively. Calculate the vapour pressure of solution containing equal weights of benzene and toluene at this temperature .

Explanation

`P_("ben")^(@)=150" torr" P_("tol")^(@)=50"torr"`
Let weight of both components = w g
Mole fraction of benzene = `(w/(78))/(w/(78)+w/(92))=w/(78)xx7176/(107w)=0.54`
Mole fraction of toluene = `(w/(92))/(w/(92)+w/(78))=w/(92)xx7176/(107w)=0.46`
`P_(T)=P_("ben")^(@)x_("ben")+P_("tol")^(@)x_("tol")=150xx0.54+50xx0.46=81+23=104` torr