Vapor Pressure

The vapor pressure of a component P _A is a measure of its volatility at any given temperature. It is essentially independent of pressure except at very high pressures. The vapor pressure of a substance is generally represented by a two-constant or three-constant Antoine equation of the type

where A, B, and C are constants and T and t are temperatures in K and C, respectively. The constant C is generally given by

where t _B is the boiling point, C.

Vapor Pressures of Immiscible Liquids

The total vapor pressure exerted by a mixture of immiscible liquids at a given temperature is the sum of the vapor pressures of the individual components at that temperature. The boiling point of a mixture of immiscible liquids is lower than that of any one of its components.

Relative Volatility ? _ij

For a vapor phase in equilibrium with its liquid phase, the relative volatility of a component i with respect to component j is given by

where y is the mole fraction of a component in the vapor phase and x is the mole fraction of the same component in the liquid phase. For a binary system, y _j =...