Modified Siwoloboff Method to Understand Isobaric Vapor-Liquid Equilibrium

Chemistry and chemical engineering undergraduate students need to understand the vapor-liquid equilibrium (VLE) phenomenon and its mathematical modeling when they study physical chemistry related courses. This contribution was inspired by the experimental work performed by chemical engineering undergraduate students when studying the VLE of binary systems. Aiming for a simple and efficient learning experience that can be easily applicable in an academic context, this paper describes a laboratory experiment to measure VLE data (bubble point temperature and liquid phase composition) of binary systems based on a modified Siwoloboff method. Although the vapor phase composition is not measured, interaction parameters for activity coefficient models can be estimated to simulate the dew point curve. This learning experience is versatile and can include VLE simulations using predictive activity coefficient models or scientific literature reports. Some learning outcomes are laboratory skills application, experimental data analysis, and programming. Not only did students gain a strong understanding of the VLE phenomenon but also they built skills like teamwork, analytic reasoning, and problem solving. The results obtained from the VLE of water + ethanol and beta-pinene + ethyl acetate showed the relative accuracy and precision of the proposed methodology.