For systems containing more than three components, pictorial representation becomes difficult, if not impossible. Simple diagrams can be obtained if the mole fractions of all but two or three components remain constant, and the variation of the two or three varying components with temperature and pressure are shown.
In practical applications, the mole fractions of all components can be expected to vary. For such systems, direct calculations based on physical models are the only way to obtain reliable information about the system phase behavior. This is the ultimate goal of this series of modules, and these calculations will be studied in detail as the course progresses.