Interactive Self-Study Module: Raoult's Law and Vapor-Liquid Equilibrium

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 differences in compositions of liquid and vapor mixtures in equilibrium is the basis for the separation of mixtures by distillation.

              This module is intended for Material and Energy Balances, Thermodynamics, and Separations courses.

    Before studying this module, you should:

    • 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. Given a vapor composition and saturation pressure versus temperature data, determine the dew temperature (at constant pressure) or the dew pressure (at constant temperature). 
    2. Use Raoult's law to calculate equilibrium compositions and/or equilibrium pressures for ideal solutions and ideal gases. 
    3. Construct a pressure-composition diagram for an ideal mixture given saturation pressures at a given temperature.
    4. Construct a temperature-composition diagram for an idea mixture given Antoine equations at a given pressure.