Mass Balances for Binary VLE
This simulation illustrates what happens to a binary mixture initially in vapor-liquid equilibrium when a pure component is added at constant temperature and pressure. If both phases remain after the addition, it illustrates how the phase mole fractions (xA is the mole fraction of A in the liquid, yA is the mole fraction of A in the vapor) remain constant. If enough of either pure component is added, the mixture is transformed to a single phase. The initial vapor-liquid mixture contains 4 mol of A and 6 mol of B at a pressure of 130 kPa. Select “add A” or “add B” and use the slider to select the amount added. If the overall mole fraction of A stays within the phase envelope, then xA and yA do not change. Selecting the “mole balance” button shows how this is possible. The size of a rectangle is proportional to the amount of that phase (blue is liquid, green is vapor). For ease of visualization, A is shown being added as a vapor and B as a liquid, but the final equilibrium is the same if A is added as a liquid or B as a vapor because the system is isothermal. For example, if pure A were added as a liquid, it would vaporize to satisfy the mass balances.
This simulation runs on desktop using the free Wolfram Player. Download the Wolfram Player here.
This simulation was made at the University of Colorado Boulder, Department of Chemical and Biological Engineering. Authors: Rachael L. Baumann, Megan Maguire
View the source code for this simulation