Desenvolvimento de planilhas excel para estimativas dos coeficientes de atividade e cálculos do equilíbrio líquido-vapor de misturas binárias em baixas pressões

Abstract

This work aims to provide Excel spreadsheets for solving problems related to the liquid-vapor equilibrium of two-component mixtures. We first discussed the nature of equilibrium, and then considered the Gibbs phase rule that gives the number of independent variables that is required to determine steady state. Then, follows a discussion on the concepts of ideality and activity. In section 3.6, a simple formulation is introduced that allows the calculation of temperatures, pressures and compositions of the phases for systems in the liquid-vapor equilibrium, known as Raoult's law, valid for systems with low and moderate pressures and generally composed by chemically similar species. Then, a modification of Raoult's law is used, which removes the restriction of chemically similar species due to the introduction of a coefficient that measures the degree of deviation from the ideal behavior of a solution (the activity coefficient). Finally, there is a discussion of these deviations from Raoult's law and the possibility of formation of azeotropes. The last topic of the theoretical review presents the equations of the models used to estimate the activity coefficients. In the methodology section, the constructions of each spreadsheet and Excel functions used for both are described through scripts. The results summarize the main behaviors presented by more than 200 analyzed systems.