#### Partially-Miscible Liquids Phase Diagrams: Interactive Simulations

##### Simulation: Vapor-Liquid-Liquid Equilibrium (VLLE)

This Demonstration shows the phase equilibrium for a binary system of two partially-miscible liquids, A and B, on a T-x-y diagram. Because of the partial miscibility, vapor-liquid equilibrium (VLE), liquid-liquid equilibrium (LLE), and vapor-liquid-liquid equilibrium (VLLE) are present on the phase diagram. The amount of of heat added is used to illustrate the system behavior. The relative amounts of each phase are determined by the lever rule (mole balance) and are shown in the bar graph. The mole fraction(s) of component B in each phase are also displayed on the bar graph for the phases present.

Try to answer these questions before determining the answer with the simulation. We suggest that you write down the reasons for your answers.

1. At what mole fraction will the temperature stay constant when heat is added? Is there more than one?
2. What vapor mole fraction can be in equilibrium with two liquid phases in this binary system?
3. Can a point on a the partially-miscible phase diagram represent more than one condition (amounts of phases)?