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

This module uses screencasts and interactive simulations to explain the lever rule, which is a way to determine the amount of each phase when two phases are in equilibrium. It results from a mass balance. The module 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 ConcepTest before watching the screencasts or working with the simulations.
  2. Watch the screencast that describes the lever rule.
  3. Use the two interactive simulations to further understand the use of the lever rule with phase diagrams.
  4. Try to solve the example problem before watching the solution in the screencast.
  5. Answer the ConcepTest.

The lever rule can be used to calculate the amount of each phase when two phases are in equilibrium.

This module is intended for a materials and energy balance or thermodynamics course.

Before studying this module, you should:

After studying this module, you should be able to:
  1. Apply the lever rule to any system that has two phases in equilibrium.