Lecture 22 reprises the three laws of thermodynamics using problems. The problems are solved in the class as illustrations of the three laws. It covers material from Chapter 18, Chemical Thermodynamics The power point presentation can be downloaded from this file. Except where noted the images are from the text. You are free to change the presentation in any way. If you wish I would appreciate the opportunity of including your version with attribution in this Libretext. My Email address is jhalpern and I am at howard.edu.