In the course of his distinguished career of over 55 years, Kenneth S Pitzer published over 360 scientific papers. Included in this volume are 72 papers, selected for their historical importance and continuing significance. In early work, where spectroscopic data were incomplete or, later on, where the systems of interest were so complex that a deductive solution from molecular information was impractical, Pitzer interrelated molecular structural information, statistical methods and thermodynamic measurements to advance the understanding of molecular systems. This volume considers all three aspects and, by putting together selected papers, highlights the cohesiveness of certain advances through time and development. Several papers from journals not widely circulated can also be found in this selection of papers.Contents:Part I — Molecules:ul>Barriers to Internal RotationRing MoleculesRelativistic Effects on Molecular PropertiesOther Papers on MoleculesPart II — Dense Phases:Extended Corresponding States and the Acentric FactorSpin Species Conversion in MethaneSemiempirical Equations for Aqueous ElectrolytesOther Condensed-State PapersReadership: Chemists, chemical engineers and geochemists.Key Features:Covers the computational side together with the theoryIncludes a wide variety of exercises, from short to research-project lengthContains historical asides and references to modular forms in mathematical culture, to help ground the subject and motivate student interest