Vapor Pressure and Boiling Point

Abstract

As one of the important chemical-engineering properties vapor pressure plays significant role for fire and explosion prevention, gas separation, design and optimization of the processes. This chapter discusses several vapor pressure equations, such as Riedel's equation, Velasco equation, Wagner equation, and Cox's equation. Most vapor pressure of chemical substances have been reported between 5 and 100 kPa. Generally, the methods for the determination of vapor pressure are divided into four groups, the static methods, dynamic methods, effusion methods, and equilibration methods. The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid. The normal boiling point of a liquid is when the vapor pressure of the liquid equals to one atmosphere. There is currently a lot of experimental data for vapor pressures of smaller molecules but data is scarce or of low quality for larger and more complex molecules of low volatility. Keywords: boiling point equation; Cox's equation; dynamic methods; effusion methods; equilibration methods; Riedel's equation; static methods; vapor pressure; Velasco equation; wagner equation