Molar free surface energy

Pavlov suggested that for all normal liquids the molar free surface energy at corresponding temperatures is proportional to the absolute temperature (cf. 7.Vin G). Stakhorsky claimed that this holds either for the surface or volume of a mol aVmlT =const. 9-90 for normal liquids between... 

In a two-phase system consisting of two or more components the composition of the discontinuity surface (see Chapter I) may significantly differ from that of a bulk of both phases in contact. Primarily the components that lower the system s free surface energy are expected to accumulate within the discontinuity surface this spontaneous concentration of substances is referred to as adsorption. The quantitative measure of the adsorption of the /-th component, T was introduced by Gibbs, and is also referred to as the adsorption, or the surface excess ofthe amount of substance. This measure has a meaning of the molar excess of a particular component per unit interfacial area ... 

The total free energy of the system is then made up of the molar free energy times the total number of moles of the liquid plus G, the surface free energy per unit area, times the total surface area. Thus... 

A very important thermodynamic relationship is that giving the effect of surface curvature on the molar free energy of a substance. This is perhaps best understood in terms of the pressure drop AP across an interface, as given by Young and Laplace in Eq. II-7. From thermodynamics, the effect of a change in mechanical pressure at constant temperature on the molar h ee energy of a substance is... 

A w Y O represents the molar free energy of replacing direct surface/water contacts by surface/surfactant contacts. The surfactants adsorb with their hydrocarbon tail directed towards a hydrophobic surface and hence we expect this term to be independent of the surfactant type and to cause a decrease in the free energy of adsorption. 

The second term on the right-hand side of Equation (86) arises from Equation (84) since chemical potential is the partial molar free energy. In this expression z, is the relative charge of the ith species and ip is the potential of the surface. 

The thermodynamics of a drop of liquid is comparatively simple. Surface tension produces a pressure which increases the partial molar free energy at any point within the drop. The escaping tendencies of material within the drop and of material in its surface are thus equalized. Considerations of this equilibrium have been recognized as fundamental in classic discussions of the thermodynamics of surface tension (18) and in investigations of pressures within, and the shapes of, bubbles and drops (2, 22). 

A relation between the parachor and zero-point molar volume Fq was proposed 3 Eucken suggested [P]=2-9Fq. De Carvalho, by assuming that the internal heat of evaporation is proportional to the free molar surface energy ( 6.VIIIG), La=kE and Trouton s rule ( 14.VIII L), LjTb= % found orF2/3/rj=const, If a is in dynes/cm. and F in cm. ... 

The first term is defined as the standard free energy of formation, = AG (7 ), which is dependent on the temperature. The second term is expressed in terms of surface energy ji for each i plane on the surface and molar surface area... 

G -G = molar free energy difference between the polymer in the crystal and the amorphous melt y = surface tension of fhe crystal embryo... 

In a simple example where a small metal particle M and a species X react to a compound MX, the excess surface energy of both reactants and products must be taken into account. Thus, the molar free energy of formation of a particle MX may be described in a simplified manner on the basis of the Gibbs concept in which excess quantities are addressed ... 

---