Interactive Self-Study Module: Entropy
Department of Chemical and Biological Engineering, University of Colorado Boulder 

This module uses screencasts and an interactive simulation to discuss the second law of thermodynamics and how to calculate entropy changes. This includes ideal gases (entropy changes in temperature and pressure), phases changes, and mixing of ideal gases. It then provides 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 four screencasts that describe how to calculate entropy and answer the questions within the screencasts (questions not yet available).
  3. Use the interactive simulation to further understand entropy when mixing ideal gases.
  4. Try to solve the two example problems before watching the solutions in the screencasts.
  5. Answer the ConcepTests.

The second law of thermodynamics is used to determine if a process is thermodynamically possible or not. 

 This module is intended for a thermodynamics course.

Before studying this module, you should:

After studying this module, you should be able to:
  1. Calculate the entropy change for reversible processes using the heat transferred and the temperature
  2. Calculate entropy changes for mixing ideal gases
  3. Calculate entropy changes for ideal gases when temperature and/or pressure change.
  4. Calculate entropy changes for phase transitions.
  5. Calculate entropy changes for liquids and solids as the temperature changes.
  6. Calculate the entropy change for an irreversible process by devising a reversible process between the initial and final conditions.
  7. Explain why work can be converted continuously completely into heat, but heat cannot be continuously converted completely into work.
  8. Predict if a process is possible based on application of the second law.
  9. Explain the second law in terms of entropy changes for system and surroundings.
  10. Explain why the entropy change is zero for a system that undergoes an adiabatic reversible process.