The document outlines a workbook designed for calculating various thermodynamic properties such as activities, activity coefficients, and excess Gibbs energies using different models like Margules, NRTL, and UNIQUAC. It provides structured spreadsheets and data input tables for systems such as methanol and benzene, facilitating both vapor-liquid and liquid-liquid equilibrium calculations. All worksheets are password-protected but allow for user modifications of specified cells to enable common calculations.