Gibbs energy repulsion

Figure 3.6. Gibbs energy vs composition diagrams of A-B systems showing the effect of (a) attractive and (b) repulsive interactions.

Gomez etal. [160] have studied specific adsorption of potassium penicillin G (salt K) on Hg electrode from electrocapillary and capacity measurements. The Frumkin isotherm has been found applicable to the quantitative description of the data repulsive interaction parameter equaled —3.5 and standard free Gibbs energy of adsorption at the zero charge was —38.6 kJ mol h depended linearly... 

Let us now consider situation with 2 0. The dependence of Gibbs energy on composition will exhibit two minima (Fig. 26) with increasing F1 copolymer will pass from the stable range (0 < F2< a) into an unstable one (a < F2 < b) and back into a stable range (F2 > b). The system will have a Tc minimum. Copolymerizations of vinyl and cyclic monomers present examples of such behaviour. The interactions of these compounds are of repulsive character coaddition is difficult to achieve. The product is a block copolymer [214] (for example styrene-/ -propiolactone [215]). At only weakly negative co values, the minimum on the Tc—F2 curve will not occur (see Fig. 27). Two local minima will, however, appear in the AG vs. F2 plot. 

The nature of the various attractive and repulsive forces that can act is discussed in the rest of this chapter. Because entropic contributions often are involved, we need to consider free energy (more precisely Gibbs energy) rather than internal energy. Especially the repulsive forces tend to depend greatly on the substances adsorbed onto particles or film surfaces, i.e., on surfactant properties and concentration. 

Gibbs Energy of Repulsion When two dispersed-phase species approach,... 

Potential Energy of Attraction—Interaction—Repulsion See Gibbs Energy of... 

Attraction, Gibbs Energy of Interaction, Gibbs Energy of Repulsion. 

Close proximity between atoms leads to synchronization of their orbiting electrons. This causes the induction of dipoles that attract each other (London-van der Waals interaction). At closer approach, the electron clouds overlap, giving rise to repulsion (Born repulsion). The variation of the Gibbs energy of dispersion interactions Gji p between two atoms with their separation distance r is given by... 

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