Prediction via the Quasi-chemical Approach

Correlation and Prediction via the Quasi-chemical Approach.—Equations (29) and (35), whose derivations involved differing definitions and assumptions, express p and V in terms of the equilibrium constants for the formation of groups of r molecules from single molecules at a particular temperature r, but for p, V, T correlation over a temperature range these equations are of limited utility, since the jfiC s are likely to be temperature dependent. In relation to equation (35), the variation of the with temperature can be expressed by the thermodynamic relation 

It may be concluded that the quasi-chemical approach offers a means of correlating p, K, T for gases which show marked departures from ideality. Thus Prausnitz et have calculated B T) for both steam and 

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