Based on the authors' graduate courses at MIT, this text and reference provides a unified understanding of both the critical concepts of chemical thermodynamics and their applications. Part I of this book provides the theoretical basis of classical thermodynamics, including the 1st and 2nd laws, the Fundamental Equation, Legendre transformations, and general equilibrium criteria. Part II contains an extensive description of how thermodynamic properties are correlated, modeled, manipulated and estimated. Both macroscopic, empirically-based and molecular-level approaches are discussed in-depth, for pure components and mixtures. New, detailed coverage shows how traditional macroscopic models are connected to their roots at the molecular level. Part III presents applications of classical thermodynamics in detail. The book connects theory with applications at every opportunity, using extensive examples, classroom problems and homework exercises. Chemical engineering and physical chemistry graduate courses in thermodynamics.