#### Energy Balances with Phase Changes: Summary

The answers to the ConcepTests are given below and will open in a separate window.
##### Key points from this module:
• The concept of state function can be used to simplify energy balances with phase changes.
• Phase changes (melting, evaporation, sublimation) have large changes in enthalpy.
• Heat of fusion is the enthalpy change when solid melts ($$\Delta H > 0$$).
• Heat of vaporization is the enthalpy change when liquid vaporizes ($$\Delta H > 0$$).
• Sensible heat is the enthalpy change when temperature changes for single-phase systems (calculate using heat capacities).
• Latent heat is the enthalpy change associated with a phase change at constant temperature and pressure.
• For an ideal mixture, the sensible heat or latent heat changes can be calculated by treating each component independently.
##### From studying this module, you should now be able to:
• Solve energy balances that involve phase changes.
• Explain the differences between sensible heat and latent heat.

Prepared by John L. Falconer, Department of Chemical and Biological Engineering, University of Colorado Boulder