State Gibbs free energy

G° = standard state Gibbs free energy R = gas content T = absolute temperature... 

AG° = the molar standard state Gibbs free energy (the change in free energy of a reaction when the products and reactants are maintained at standard conditions)... 

Table 8.17 Main predominance limits of aqueous complexes and saturation limits between solutes and condensed phases in iron-bearing aqueous solutions (see figure 8.22). Standard state Gibbs free energies of formation of species are listed in table 8.18. (c) = crystalline ... 

Cesium, Cs, and rubidium, Rb, form ideal solutions in the liquid phase, and regular solutions in the solid phase. Their standard state Gibbs free energy changes of melting as a function of temperature, AG c. = (G°cs.l 0,5) and = (G° - G°, 5) respectively, are... 

It can be shown (see Chapter 3) that the standard state Gibbs free energy change for this reaction is given by the difference between the standard state free energies of the products minus the reactants and can be related to the partial pressure of the gaseous species ... 

The variation of the standard state Gibbs free energy change for the oxidation reaction at any temperature from experimentally measured variations in Po2,e r can be fitted to an equation of the form ... 

AGf Standard-state Gibbs free energy of formation J/mol... 

Since ArG° is the standard state Gibbs free energy change, the pressure is specified. Hence, (dArG°/dp)T = 0, and from equation (11.102) we get... 

Consequently, by measuring the zero-current cell potential we obtain the standard state Gibbs free energy change on reaction (if all the ions are in their standard states). Now if we continue further and measure how the zero-current standard state cell potential varies as a function of temperature, we have... 

In this way Rosing and Slater [Biochun. Biophys. Acta 267, 275 (1972)] were able to measure the standard-state Gibbs free energy change for this reaction to be —34 kJ/mol at one set of conditions. 

As with all chemical reactions, the standard state Gibbs free energy change for an isotope exchange reaction at a given pressure and temperature is related to the equilibrium constant by ... 

Solubility of a Pure Component Strong Electrolyte. The calculation of the solubility of a pure component solid in solution requires that the mean ionic activity coefficient be known along with a thermodynamic solubility product (a solubility product based on activity). Thermodynamic solubility products can be calculated from standard state Gibbs free energy of formation data. If, for example, we wished to calculate the solubility of KCI in water at 25 °C,... 

If AG° is the standard state Gibbs free energy change per mole of monomer, one obtains the following expression when Equation 4.9 is applicable ... 

S° for the species taking part in the reaction. See Example 2.6 for details. The standard-state Gibbs free energy of reaction can likewise be calculated from the Gibbs free energies of the constituent species, or alternatively, once A// and are obtained, AG can be obtained from the relationship AG = AH - TAS. 

Since the short range contribution was developed as a symmetric model, the reference states were pure solvent and completely ionized pure electrolyte, which may be hypothetical. The reference state Gibbs free energies per mole are thus expressed as ... 

Secondly, infeasible and not hazardous reaction pathways among all hte possible pathways are excluded. The smaller value of standard state Gibbs free energy for the reaction, A/J, the higher feasibility of the reactions(Alberty, 1987). And energy potential (heat of reaction) of the reaction by measuring heat flux. The AT/, and Cp can be calculated from the enthalpy of formation, AHf for each component. But the thermodynamic properties were unknown, so group contribution method is used in this step. 

The most striking feature of the comparison of energies of structures and intermediates obtained from computations is the large difference in transition state Gibbs free energies and enthalpies in the presence and absence of the counter ion and two explicit water molecules. These differences are due to the large positive reaction entropies due to association of the Na and water molecules with the intermediates and transition states. Another importance conclusion that can be drawn is that the enthalpies of reaction are only mildly affected by the identity of the nitroalkane. The structures of intermediates and transition states for the reactions of the nitroalkanes with hydroxide ion in the presence of sodium ion in aqueous solution are illustrated in Scheme 1.18. 

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