In this experiment you will learn about the concept of vapour liquid equilibrium for binary liquid mixtures by generating vapour liquid equilibrium (VLE) data (Teq-xeq-yeq) at constant pressure using an Othmer's still. Owing to inherent errors in the experimental procedure the data generated may not be thermodynamically consistent. Therefore you will also learn to establish the thermodynamic consistency of the data. The VLE data generated are fitted in convenient mathematical models which describe the given system based on a few system specific parameters. In this experiment you will learn to fit the vle data by two thermodynamic models namely Margulas and Van laar