Saturation vapour pressures of organic compounds

To estimate the thermodynamic properties of mixtures, it is first necessary to know the corresponding properties of each of the pure substances present in the mixture.

A mixture of a given composition, placed in a cell thermostated at temperature T and pressurized to pressure p, is frequently two-phase. The most commonly encountered case is that of liquid-vapor equilibrium (the liquid phase is in equilibrium with the vapor phase above it). This is, for example, what happens on the plates of a distillation column.

In order to calculate the composition of the liquid and vapor phases in equilibrium at a given temperature and pressure, it is necessary to know precisely the vapor pressure of each of the pure substances present in the mixture under consideration. This is the aim of this article, which provides easy-to-use correlations for calculating the vapor pressure of a pure substance at any temperature. Their accuracy is close to the experimental precision with which vapor pressures can be measured.