Nonanalytic Vapor Pressure Equation With Data for Nitrogen and Oxygen.

Abstract

The specific heat of a two phase liquid-vapor system at constant volume apparently increases without limit at temperatures approaching the critical point, suggesting (via a thermodynamic relation) that the vapor pressure derivative d2P/dT2 may behave similarly. This nonanalytic behavior at the critical point is used in the present vapor pressure formula to gain simplicity and accuracy, as seen by use of data for nitrogen and oxygen.