This study guide deals with the application of thermodynamics to the description of the properties of materials. It covers the qualitative behavior of single and multicomponent mixtures, including vapor-liquid, liquid-liquid, and solid-liquid phase equilibria. It also explains the use of activity coefficient models and equations of state for the quantitative prediction of phase behavior and chemical reaction equilibria. The guide assumes a prior basic understanding of first and second laws of thermodynamics and multivariate calculus.