Charts Using the Convergence Pressure

Determination of K values for a given mixture according to this approach requires therefore - in addition to specification of the temperature and pressure - the evaluation of the convergence pressure. The procedure is given by Hadden and Grayson (1961), and it is applicable  

An extension to compounds with higher normal boiling points is given by Kesler et al (1977). 

The method provides successful prediction of K values, with somewhat poorer results in the presence of H2 and/or CH4. [Dowling and Todd (1973), for example, report an overall error of 13.6% in K values for 253 data points in methane-containing systems and of 16.7% for 206 points in hydrogen-containingsystems.] Its major drawback is that it cannot be easily adapted for computer use. 

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