Interactive Self-Study Module: Immiscible Liquid Phase Diagrams

This module uses screencasts and interactive simulations to explain the vapor-liquid phase equilibrium of two liquids that form an ideal solution. Both pressure-composition and temperature-composition diagrams are explained. It then provides step-by-step quiz simulations and example problems to allow the user to test themselves. We suggest using the learning resources in the following order:

    1. Attempt to answer the multiple choice ConcepTests before watching the screencasts or working with the simulations.
    2. Watch the screencast that describe the phase diagrams and answer the questions within the screencast.
    3. Use the interactive simulation to further understand the behavior of the phase diagrams.
    4. Work through the two quiz interactive simulations to test your understanding by preparing phase diagrams step-by-step.
    5. Try to solve the two example problems before watching the solution in the screencast.
    6. Answer the ConcepTests.


    The phase diagrams for immiscible liquids helps understand solid-liquid phase diagrams that have multiple solid phases.

    This module is intended for a Thermodynamics course and may also be useful for a Materials course.


    • Understand single-component vapor-liquid equilibrium
    • Be able to apply the Antoine equation to determine saturation pressure of a single component at a given temperature
    • Be able to calculate partial pressures for a mixture of ideal gases

    After studying this module, you should be able to:
    1. Construct a pressure-composition diagram at a given temperature for two immiscible liquids, given saturation pressures at that temperature.
    2. Construct a temperature-composition diagram at a given pressure for two immiscible liquids, given Antoine equations
      (saturation pressure versus temperature) for each component.
    3. Determine what phases are present, given temperature, pressure, saturation pressures, and overall compositions.
    4. Given a vapor composition and saturation pressure data, determine the temperature (at constant pressure) or the pressure
      (at constant temperature) at which one or more components condenses.