This text, now in its fourth edition, continues to provide a concise introduction to chemical thermodynamics. An examination of equilibrium in the everyday world of mechanical objects provides the starting point for an account of the factors that determine equilibrium in chemical systems. This approach leads students to an understanding of the underlying principles of thermodynamics, which are then applied to a wide range of physicochemical systems. The book also discusses the problems of non-ideal solutions and the concept of activity, and provides an introduction to the molecular basis of thermodynamics. The book has been revised for this new edition, with illustrations and text presented in a new, larger format. The author has updated dimensions and included new problems and worked examples.