Single-Component Phase Equilibrium: Interactive Simulations
Try to predict the behavior when a parameter changes before using a slider to change that parameter. Screencasts explain how to use these simulations.
Simulation: Pressure-Temperature Phase Diagram for Water
Try to answer these questions before determining the answer with the simulation. We suggest that you write down the reasons for your answers.
- Which phase change requires the most heat to go from one phase to another isobarically?
- When undergoing a phase change isothermally, where is the biggest specific volume change?
Try to answer these questions before determining the answer with the simulation. We suggest that you write down the reasons for your answers.
- If a vapor-liquid mixture is heated in a fixed volume container does it eventually become all liquid or all vapor?
- Can a liquid be converted to a vapor without a visible phase change?
In this simulation, liquid propane or liquid toluene is injected into an evacuated 2-L spherical tank that is held at constant temperature. When propane is injected, it either vaporizes completely or forms two phases in vapor-liquid equilibrium (VLE), depending on the number of moles injected and the temperature (control both with sliders). Because toluene has a much lower saturation pressure, only a small amount of injected toluene liquid vaporizes. When the component is in VLE, the tank pressure equals the saturation pressure; otherwise, the pressure is calculated using the ideal gas law. The pressure is displayed at the top of the tank. Click the “inject” button to inject liquid into the tank. Press “reset” at any time to start from the beginning. The intensity of the blue color of the vapor is proportional to the vapor density. The liquid volume in the tank is exaggerated relative to the vapor volume for better visualization. The bar graph on the right shows the number of moles of liquid and vapor in the tank.
Try to answer these questions before determining the answer with the simulation. We suggest that you write down the reasons for your answers.
- If 0.15 L of liquid are injected into a 2-L evacuated tank, what are the possible phases present at equilibrium?
- Suppose when 0.10 L of toluene are injected isothermally into an evacuated tank and vapor and liquid are present at equilibrium. What phases are present if an additional 0.10 L of toluene is injected?
- Suppose 1.0 mol of propane is injected into an evacuated tank and 0.03 mol of liquid propane is present at equilibrium. If 0.90 mol of propane were injected in the evacuated tank at the same temperature, approximately how many moles of liquid propane would be present?
Here is another optional simulation that shows the circumnavigation of the critical point on a pressure-temperature diagram.