Change of the Gibbs free energy

The free energy functions are defined by explicit equations in which the variables are functions of the state of the system. The change of a state function depends only on the initial and final states. It follows that the change of the Gibbs free energy (AG) at fixed temperature and pressure gives the limiting value of the electrical work that could be obtained from chemical transformations. AG is the same for either the reversible or the explosively spontaneous path (e.g. H2 -I- CI2 reaction) however, the amount of (electrical) work is different. Under reversible conditions... 

One can interpret the log-uniform distribution through the Arrhenius law k — Aexp(—AG/fcT), where AG is the change of the Gibbs free energy inreaction (it includes both energetic and entropic terms AG = AH—TAS, where AH the enthalpy change and AS the entropy change in reaction, T the temperature). The log-uniform distribution of k corresponds to the uniform distribution of AG. 

Fig. 5. The potential energy surfaces of the initial and final states at different ratios between the reaction exothermicity, J, and the reorganization energy, Er. As a rule, for exothermic reactions in condensed media, J is assumed to be equal to the change of the Gibbs free energy, - AG°.

At constant temperature and pressure, the affinity of the chemical reaction is the negative of the change of the Gibbs free energy... 

Several important points must be made in connection with Table 1.16.1 (i) There is a common misconception to the effect that the performance of work is exclusively associated with a change in the internal energy of the system. Clearly, in general this is not the case. If, for example, a process is carried out at constant T and P, then the performance of work other than P-V work is associated with a change of the Gibbs free energy. (ii) For each of the five conditions under which processes are shown to occur in Table 1.16.1, there is a special function of state best suited to describe the process furthermore, under the various indicated conditions the inexact... 

The costs of electrochemical processes are closely connected to the energy efficiency or energy yield, which is either related to the change of the Gibbs free energy of the reaction AG... 

It was mentioned above that from the APD, valuable information on various OMC properties can be obtained. Before this is outhned in detail, the calculation of the APD is briefly reviewed. The adsorption potential A) is defined as the negative change of the Gibbs free energy of adsorption ... 

We repeat the discussion of section 2.3.3 which culminated in eqn (2.46), but now clarified by the kinematic description of the previous section. Recall that the basic argument consisted of two parts. First, we construct a function (if the number of configurational coordinates is finite) or a functional (if the configurational coordinates are specified by a function) which is the sum of the time rate of change of the Gibbs free energy G( r, r, ) and a dissipative potential F( ri r ), of the form... 

If dnA moles of A react, then, according to the stoichiometry of the reaction, they will also consume (b/a)dn moles of B and produce (c/a)dna moles of C and (d/a)dna moles of D. The corresponding change of the Gibbs free energy of the system at constant T and p is, according to (10.15)... 

Kirkwood (1934) has shown that the change of the Gibbs free-energy AOf, due to electrostatic interactions when a molecule is transferred from a medium of imit dielectric constant to the solvent is... 

In these cases, the method of parametric sensitivity analysis has received the broadest acceptance. In this method, often the calculation of time profiles of the derivatives of species concentrations is made by the values of rate constants in individual steps as the initial computing procedure [58,59]. Also, methods are applied to analysis the rates of individual steps and to separate the contributions of individual steps in the total change of the Gibbs free energy or entropy that enter into the overall chemical transformations [60]. 

The measured emf can be easily expressed in change of the Gibbs free energy by... 

The change of the Gibbs free energy caused by the formation of a nucleus is determined by the following expression ... 

To establish the most probable mechanism for formation of hydrogenated flirans under Prins reaction conditions, the total change of the Gibbs free energy (A G gg) of generation of the allylic alcohol and the allylic alcohol ester, being precursors of the unsaturated alkoxycarbenium and the dioxolenium ions, has also been calculated. 

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