Nonelectrolytes from experimental data

DETERMINATION OF NONELECTROLYTE ACTIVITIES AND EXCESS GIBBS FUNCTIONS FROM EXPERIMENTAL DATA... 

Figure 11. Observed and predicted aqueous solubilities of nonelectrolytes (o) and weak electrolytes ( ). The solid line is the theoretical line described by Equation 22. The dashed line is the regression line of the experimental data. (Reproduced with permission from Ref. 38. Copyright 1983 American Pharmaceutical Association.)...

Before presenting examples, we should remark that the subject of solubility of nonelectrolytes has been treated in detail by Hildebrand and Scott (921). They discuss (in their Chapter XI) the various chemicaT and physical theories of the interactions, such as H bonding, that are responsible for extreme deviations from regular behavior. Both approaches can provide equations to fit experimental data. The first does so by relating equilibrium constants and activity coefficients for assumed reactions, and the second by the use of varying values of the energy of interaction and empirical factors for the effective volume of solute and solvent molecules. They conclude with the observation, still valid, that no satisfactory theoretical treatment is available. 

The second part of this series extends the ideas of free volume to liquids. It is only in the third part that Frank and Evans apply the concept of free volume to aqueous solutions. Examining the experimental data on aqueous solutions of nonelectrolytes, they found striking deviations from the standard behavior. These findings led to the now famous conclusion ... 

In this seetion, we intend to present some simple and straightforward aspects of adsorption of nonelectrolytes from binary liquid solutions on to mineral surfaces. Owing to the vast literature on this subject, we limit the presentation to a description of some frequently observed adsorption isotherms applicable to experimental data represented by the adsorption of polar molecules on to mineral oxide surfaces from dilute nonaqueous solutions. 

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