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Energy Balances with Phase Changes: Summary
The answers to the ConcepTests are given below and will open in a separate window.
ConcepTest 1 Answer
ConcepTest 2 Answer
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
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