#### Interactive Self-Study Module: Gibbs Free Energy and Phase Separation

##### Overview:

This module uses a screencast and interactive simulations to explain Gibbs free energy and phase separation. It then provides example problems and concepTests to allow the user to test themselves. Your retention of material in this module will increase if you write down reasons for your answers to ConcepTests, the question in the screencast, and questions to answer before using interactive simulations, and you try to solve the example problems before watching the screencast solutions. We suggest using the learning resources in the following order:

- Attempt to answer the multiple-choice ConcepTest and solve the example problem before watching the screencasts or working with the simulations.
- Watch the screencast that shows how liquid-liquid phase separation is related to the Gibbs free energy of mixing and answer the question within the screencast.
- Review important equations for Gibbs free energy and phase separation.
- Use the interactive simulations to further understand the Gibbs free energy and miscibility.
- Try to solve the example problems before watching the solutions in the screencasts.
- Answer the ConcepTests.
- Look at the list of key points, but only after you try to list the key points yourself.

##### Motivation:

- This module is intended for a thermodynamics class.

##### Before studying this module, you should be able to:

- Calculate vapor-liquid equilibrium for non-ideal solutions.
- Apply the lever rule to determine the amounts of two phases in equilibrium.

##### After studying this module, you should be able to:

- Explain how phase stability is related to minimizing Gibbs free energy at constant temperature and pressure.
- Predict phase separation from Gibbs free energy dependence on composition.
- Interpret the meaning of large activity coefficients and what they indicate about phase separations.
- Calculate equilibrium phase compositions, given activity coefficients and some phase compositions.