At high pressures, both the vapor and liquid phases may be nonideal. Consider a binary mixture of a and b with vapor-phase mole fraction and T known. Develop a set of equations and a solution algorithm to determine the composition in the liquid phase and the system pressure.
Use the van der Waals equation to quantify deviations from ideality in the vapor and the threesuffi x Margules equation to model the nonideal liquid. Assume that critical properties, liquid volumes, and Antoine coeffi cients for each species are readily available and that the threesuffi x Margules parameters have been determined.