This is a revision edition for first year students of chemistry and chemical engineering. As before, it presents thermodynamics using practical chemical examples in a way that uses very little mathematics. The concepts of entropy, (Gibbs) free energy, chemical potential and available work are introduced in this volume: it explains their scope and the links between them for students who may not have met them before. The book includes a discussion of experimental equilibrium data, an introduction to electrochemical cells, free energy in industrial processes and a chapter on phase equilibria. There is an appendix on mathematical methods. All the examples and problems have been revised and in many cases replaced with more topical ones from biological systems, heat and power conservation, pollution, etc. The notation and conventions have been brought into line with current practice.