Interactive Self-Study Module: Entropy


This module uses screencasts and interactive simulations 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. Your retention of material in this module will increase if you write down reasons for your answers to ConcepTests, questions in screencasts, 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:

  1. Attempt to answer the multiple-choice ConcepTest and solve the example problem before watching the screencasts or working with the simulations.
  2. Watch the screencasts that describe how to calculate entropy and answer the questions within the screencasts.
  3. Review important equations for entropy.
  4. Use the interactive simulations to further understand entropy when mixing ideal gases.
  5. Try to solve the example problems before watching the solutions in the screencasts.
  6. Answer the ConcepTests.
  7. Look at the list of key points, but only after you try to list the key points yourself. 
  • 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 be able to:
After studying this module, you should be able to:
  • Calculate the entropy change for reversible processes using the heat transferred and the temperature
  • Calculate entropy changes for mixing ideal gases
  • Calculate entropy changes for ideal gases when temperature and/or pressure change.
  • Calculate entropy changes for phase transitions.
  • Calculate entropy changes for liquids and solids as the temperature changes.
  • Calculate the entropy change for an irreversible process by devising a reversible process between the initial and final conditions.
  • Explain why work can be converted continuously completely into heat, but heat cannot be continuously converted completely into work.
  • Predict if a process is possible based on application of the second law.
  • Explain the second law in terms of entropy changes for system and surroundings.
  • Explain why the entropy change is zero for a system that undergoes an adiabatic reversible process.