Vapor-Liquid Equilibrium For Non-Ideal Solutions: Example Problems

Try to solve these problems before watching the solutions in the screencasts.

Example Problem 1

A vapor-phase mixture of components 1 and 2  is compressed at fixed temperature until the vapor completely condenses. The vapor contains 30 mol% component 1 and 70 mol% component 2. The saturation pressures for components 1 and 2 at the temperature of the system are 0.82 and 1.93 bar, respectively. The bubble pressure of a 50:50 mixture of components 1 and 2 is 1.08 bar. 
    a) Estimate the pressure require to completely liquify the 30:70 mixture, assuming that the
        excess Gibbs free energy of the liquid is well-modeled by the one-parameter Margules            equation.
    b) Would the required pressure to liquify the mixture be higher or lower if components 1 and
        2 formed an ideal solution? 

Example Problem 2

Calculate the bubble pressure of a binary system. The mole fraction of component 1 in the liquid phase is 0.40 and the pressure is 70 kPa. The saturation pressures: