Question

At 85oC, the vapor pressure of pure o-xylene is 55 Torr and the vapor pressure of pure p-xylene is 85 Torr. When liquid o-xylene is mixed with liquid p-xylene, the solution formed is ideal at all compositions.

(a) Calculate ∆G, ∆H, and ∆S of mixing when liquid o-xylene and liquid p-xylene are mixed at 85oC, given that the mole fraction of p-xylene is 0.30 and the solution contains a total of 4.0 mol of material.

(b) What are the mole fractions of o-xylene and p-xylene in the vapor at equilibrium with this solution?

Answer 1

(a) Since o-xylene and p-xylene form ideal solution upon mixing, there would be no enthalpy change (property of ideal solutions). Hence ∆H = 0