Availability of Experimental Vapor Pressure Data and Estimation Methods

Availability of Experimental Vapor Pressure Data and Estimation Methods 

An attractive alternative to the direct measurement of vapor pressure is the use of gas chromatographic retention to estimate p (e.g., Hinckley et al., 1990). This method is based on the evaluation of the partitioning behavior of a given compound between the gas phase (i.e., the mobile phase) and a bulk organic phase (i.e., the stationary phase) at different temperatures. The method hinges on the selection of an 

Finally, very often vapor pressures are reported only for one particular temperature (e.g., 20°C or 25°C, as in Appendix C). Since vapor pressure is strongly dependent on temperature, it is necessary to be able to extrapolate such values over the ambient temperature range. Hence, it is necessary to know the enthalpy of vaporization or sublimation at ambient temperature. As we have seen in Section 4.3, for liquid compounds, a proportionality between AvapHt and is observed (Fig. 4.5). This 

Note that in contrast to Fig. 4.7, we use the decadic logarithm in Eq. 4-29 and that this relationship holds over a very large vapor pressure range ( 15 orders of magnitude). 

Assuming that this Avap/7, value is constant over the ambient temperature range, it can be used to estimate pH at other temperatures (see also Eq. 3-51)  

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