Raoult's Law and Vapor-Liquid Equilibrium: Summary

Key points from this module:
1. Raoult's law assumes ideal gases and ideal liquid solution. For similar molecules (e.g., n-hexane and n-octane), Raoult's law may be a good approximation.
2. When a vapor mixture is cooled or its pressure is increased, both components condense.
3. Bubble pressure is the pressure where the first bubble of vapor forms as the pressure above a liquid decreases at constant temperature.
4. Bubble temperature is the temperature where the first bubble of vapor forms as the temperature of a liquid increases at constant pressure.
5. Dew pressure is the pressure where the first drop of liquid forms as the pressure of a vapor increases at constant temperature.
6. Dew temperature is the temperature where the first drop of liquid forms as the temperature of a vapor decreases at constant pressure.
7. Unlike a pure component, at constant pressure a mixture does not evaporate at constant temperature.

After studying this module, you should be able to:
1. Given a vapor composition and saturation pressure versus temperature data, determine the dew temperature (at constant pressure) or the dew pressure (at constant temperature).
2. Use Raoult's law to calculate equilibrium compositions and/or equilibrium pressures for ideal solutions and ideal gases.
3. Construct a pressure-composition diagram for an ideal mixture given saturation pressures at a given temperature.
4. Construct a temperature-composition diagram for an idea mixture given Antoine equations at a given pressure.