The aim of this contemporary textbook is to show students that thermodynamics is a useful tool, not just a series of theoretical exercises. Written in a conversational style, the text presents the second law in a totally new manner--there is no reliance on statistical arguments; instead it is developed as a natural consequence of physical experience. Students are not required to write complex, iterative computer programs to solve phase equilibrium problems--techniques are presented which enable use of readily available math packages. The book also explores electrochemical systems such as batteries and fuel cells. Included in the extensive amount of examples are those which demonstrate the use of thermodynamics in practical design situations.