Enthalpic and entropic parts

A further insight into the nature of the hydrophobic interaction is obtained by separating the free energy into enthalpic and entropic parts... 

Fig. 3. Representation of the parameter X and its enthalpic and entropic parts, XH and Xs, respectively, versus reduced temperature as calculated from Eqs. (20) and (21). The parameters are the same as in Fig. 2...

So, for very fast reactions, the theory predicts a variation of a with potential. There is some evidence that this occurs, but given the multistep nature of any electrode reaction no definitive conclusions can be taken, and mechanisms can be elaborated which have constant charge transfer coefficients. Indeed the fact that the enthalpic and entropic parts of the coefficients have different temperature dependences leads to the question as to what is the real significance of the charge transfer coefficient, a topic currently under discussion9. 

When very accurate data In on K as a function of T are available, the corresponding standard Gibbs energies (-RT In Ky) can be split into their enthalpic and entropic parts (sec. 1.2.15), of which the former virtually represents the enthalpy of the exchange of 1 against J under standard conditions, which can be related to the difference A, H - A, H ... 

In this notation is expressed as composed of the enthalpic and entropic parts, Xh d... 

Fig. 15 Enthalpic and entropic parts of FH parameters for the three dPB/PS blends versus pressure. In all cases a decrease with pressure is found. The lowest numbers are found for the PB copolymer mixtures which saturates above 100 MPa...

The strength of the interaction between two polymers can be considered as a criterion for miscibility since for high polymers the interaction parameter needs to be negative. Several reviews of the techniques can be found in the literature. Most experimental methods for measuring the interaction parameter give the total interaction including both enthalpic and entropic parts or, in terms of the equation of state theory, X 2 TvQ 2- One noted exception to this is heat of mixing measurement, which by definition includes only enthalpic contributions. 

Knowing the temperature dependence of x, it is possible to split this quantity in its enthalpic and entropic part and xs). 

An important part of the optimization process is the stabilization of the monomer-template assemblies by thermodynamic considerations (Fig. 6-11). The enthalpic and entropic contributions to the association will determine how the association will respond to changes in the polymerization temperature [18]. The change in free volume of interaction will determine how the association will respond to changes in polymerization pressure [82]. Finally, the solvent s interaction with the monomer-template assemblies relative to the free species indicates how well it will stabilize the monomer-template assemblies in solution [16]. Here each system must be optimized individually. Another option is simply to increase the concentration of the monomer or the template. In the former case, a problem is that the crosslinking as well as the potentially nonselective binding will increase simultaneously. In the... 

The thermoelastic behavior of these materials has also been reported [188]. Such experiments resolve the nematic to isotropic transition into entropic and enthalpic contributions as already described, and provides values of the corresponding energetic and entropic parts of the force, fe and fs [175] (see Section 7). 

The interaction that arises from the overlapping of the surfactant chains is due to a complex interplay between enthalpic and entropic effects involving surfactant chain segments (monomer units) and solvent molecules. The enthalpic part of the... 

The use of water as a medium for promoting organic reactions has, for the most part, been non-existent, despite the fact that water has served, and continues to serve, as the solvent in which the vast majority of biochemical processes take place. Chemists have only recently come to appreciate the enormous potential that water holds for those engaged in synthetic organic and organometallic chemistry, in part because of water s unique enthalpic and entropic properties. 

For more than two decades researchers have attempted to overcome the inadequacies of Flory s treatment in order to establish a model that will provide accurate predictions. Most of these research efforts can be grouped into two categories, i.e., attempts at corrections to the enthalpic or noncombinatorial part, and modifications to the entropic or combinatorial part of the Flory-Huggins theory. The more complex relationships derived by Huggins, Guggenheim, Stavermans, and others [53] required so many additional and poorly determined parameters that these approaches lack practical applications. A review of the more serious deficiencies... 

The AGp of reaction between pure components may be split into enthalpic, entropic, and volumetric parts ... 

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