Molar surface excess entropy

Wu T-Y, Chen B-K, Kuo C-W, Hao L, Peng Y-C, Sun I-W (2012) Standard entropy, surface excess entropy, surface enthalpy, molar enthalpy of vaporization, and critical temperature of bis(trifluoromethanesulfonyl)imide-based ionic liquids. J Taiwan Inst Chem Eng 43 860-867... 

In the general case, the integral molar entropy of adsorption is not equal to the mean differential entropy of adsorption over the range of surface excess concentration from 0 to r, because of the extra term of the right-hand side of Equation (2.67). 

It is sometimes convenient to rewrite the adsorption equation in other more symmetrical forms. In a system of c components we can specify the state by the values of (c + 1) independent densities, for example, the c molar densities and the entropy density, i). Let all these densities be denoted by the symbol p, a vector of (c +1) components, and their surface excesses F. Shnilaily let e be the oonjugnte set of fields.t In the example given the first c of these would be the chemical potentials and the last would be the temperature. The adsorption equation (2.31) can then be written in more symmetric form... 

Further information is obtained if the amount of liquid adsorbed on the surface of the particle is also determined, permitting the combination of the data on heat of immersion with those on the amount of adsorbed liquid. Thus, molar adsorption enthalpies can be given for the characterization of the stabilizing adsorption layer [12-16]. A further benefit of adsorption excess isotherms is that it is possible to calculate from them the free enthalpy of adsorption as a function of composition. When these data are combined with the results of calorimetric measurements, the entropy change associated with adsorption can also be calculated on the basis of the second law of thermodynamics. Thus, the combination of these two techniques makes possible the calculation of the thermodynamic potential functions describing adsorption [14,17-19]. 

Staverman uses Flory s model as a starting point, but introduces a form factor in the number of complexions, taking account of the fact that the molecules are only in contact at their surfaces. This enables him to construct a new expression for number of possibilities of introducing the molecule of polymer and the molecules of solvent. Thus, the excess molar entropy term of conformation is altered, and becomes ... 

---