Vapor Pressure Data Analysis and Statistics
Technical Report,01 Nov 2015,30 Apr 2016
Army Edgewood Chemical Biological Center Aberdeen Proving Ground United States
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This report compares several methods for expressing vapor pressure as a function of temperature also referred to as correlation in the traditional literature using the Antoine equation and discusses statistical analyses of the resulting correlations. Vapor pressure varies nonlinearly with temperature and is an important property of materials for applications ranging from estimates of their behavior in the environment to design of test equipment. Vapor pressure and temperature measurements over wide dynamic ranges are difficult to obtain, and prediction of vapor pressure based on limited data may be required in certain cases, necessitating reliable relationships between pressure and temperature. While the integrated form of the Clausius--Clapeyron equation has sound theoretical basis for correlating pressure and temperature, assumptions required for the temperature dependence of enthalpy may not be valid, particularly over wide temperature ranges. To correct for those approximations, a modified correlation equation may be implemented to enable accurate extrapolation. One variation of the Clausius-Clapeyron equation is the Antoine equation, which incorporates a third fit parameter to more accurately describe the nonlinearity of vapor pressure data. The current results support the use of the procedure proposed by Penski and Latour as the best method for correlating vapor pressure data.