Ideal method

The Ideal method uses the ideal gas law and Raoult's law to determine the vapor and liquid compositions and thereby calculate thermodynamic properties by using standard mixing rules. Typically, you use this method only for ideal systems.

An ideal system is a system composed of ideal gases and liquids. An ideal gas follows the ideal gas law (PV = nRT) and has a fugacity of 1. An ideal liquid follows Raoult’s law and has an activity coefficient of 1. We can assume ideal behavior for gases at vacuum and low pressure or at very high temperatures. We can assume ideal behavior for liquids when there are very small interactions (or interactions that cancel each other) between the liquid molecules. Interactions are negligible when we mix molecules of similar size and character together in the liquid phase.