At 25°C the vapor pressures of benzene and toluene are 96.0 mm Hg and 30.5 mm Hg,respectively.When a 1:1 molar mixture of benzene and toluene is fractionally distilled,the first fraction will have a mole fraction of benzene that is closest to

Question

Quizplus · Accepted Answer

The mole fraction of benzene in the first fraction can be calculated using the following equation:

Xbenzene = Pbenzene / Ptotal

where Pbenzene is the vapor pressure of benzene and Ptotal is the total vapor pressure of the mixture.

At 25°C, Ptotal = Pbenzene + Ptoluene = 96.0 + 30.5 = 126.5 mm Hg

So, Xbenzene = 96.0 / 126.5 = 0.759

Therefore, the closest choice is C, which corresponds to a mole fraction of benzene of 0.7.

At 25°C the Vapor Pressures of Benzene and Toluene Are