Heat of Surface Formation and Evaporation

In order to understand how liquids are stabilized, several attempts have been made to relate the surface tension of a liquid to the latent heat of evaporation. It was argued a 

The ratio of the enthalpy of surface formation to the enthalpy of vaporization, hs hvap, for various substances is given in Table 2.2. Substances with nearly sphericalshaped molecules have ratios near 1/2, while substances with a polar group on one end have a much smaller ratio. This difference indicates that the latter molecules are oriented with the nonpolar end toward the gas phase and the polar end toward 

Enthalpy of Surface Formation, hs [10 erg/molecule], and Ratio to Enthalpies of Vaporization, hvap 

In fact, any deviation from Stefan s law is an indication that the surface molecules are oriented differently from those in the bulk phase. This observation is useful in order to understand surface phenomena. 

As an example, one may proceed with this theory and estimate the surface tension of a liquid with data on its heat of evaporation. The number of near neighbors of a surface molecule will be about half (6 = 12/2) than those in the bulk phase (12 neighbors). It is now possible to estimate the ratio of the attractive energies in the bulk and surface phases per molecule. We have the following data for a liquid such as CC14  

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