Gibbs energy of association

Logarithms of formation constants, which are proportional to the Gibbs energies of association, are often tabulated. The logarithms of formation constants and pK t values of dissociation constants are identical (Eq. 6-72) and are a measure of the standard... 

In general, the corresponding A(AH) and A(A5) values can be obtained as the differences A//r - AHs and ASr - ASs, or can be estimated from the selectivity factor (a), which is related to the difference in Gibbs energy of association A(AG) for an enantiomeric pair as was already mentioned. The values of A(AH) and A(A5) obtained by the two methods should be identical within experimental error. 

FIGURE 11.7 Gibbs energy of association as a function of the number (/) of monomers in the aggregate. 

This variation is associated with the Gibbs energies of solution. Ast, G of the compounds. These, and the values of the enthalpies of solution, ASoi H - and the entropy changes of solution. when the compounds... 

The partial structure factors for binary (Bhatia and Thorton, 1970) and multicomponent (Bhatia and Ratti, 1977) liquids have been expressed in terms of fluctuation correlation factors, which at zero wave number are related to the thermodynamic properties. An associated solution model in the limits of nearly complete association or nearly complete dissociation has been used to illustrate the composition dependence of the composition-fluctuation factor at zero wave number, Scc(0). For a binary liquid this is inversely proportional to the second derivative of the Gibbs energy of mixing with respect to atom fraction. 

In the development of the associated solution model used a number of general features have been obtained, which hopefully should prove useful. In particular it is shown in Appendix that the model behavior includes the occurrence of miscibility gaps in the liquid that do not require interaction coefficients that are large in magnitude and that are associated with an uncommon form for the Gibbs energy of mixing isotherms. 

Since AG = AH - TAS, the net result is a negative value of AG, a "hydrophobic effect" that favors association of bases. Substantial efforts have been made to estimate quantitatively the Gibbs energies of formation of helical regions of RNA molecules in hairpin stem-loops such as that of Fig. 5-9. 4 45 49-54 Table 5-2 shows the observed increments in AGf° of such a helix upon addition of one base pair at the end of an existing helix. Addition of an AU pair supplies only -4 to -5 kj... 

Electrode Potentials of Mitochondrial Electron Carriers and Gibbs Energy Changes Associated with Passage of Electrons3... 

An equilibrium electrical potential is associated with a Gibbs energy of formation by the equation... 

Abbreviations A H Huggins coefficient M, molar mass R, radius of gyration RD, core radius p, association number AmcH°, standard enthalpy of micellization, AmlcG°, standard Gibbs energy of micellization A2, second virial coefficient. Ru, hydrodynamic radius. 

Thermodynamics is used to predict whether reactants have a spontaneous tendency to change into products. This tendency is associated with a decrease in the free energy or Gibbs energy of the system (G) to a minimum. As a consequence, the thermodynamic criterion for spontaneous change at constant temperature and pressure is AG < 0. Under standard conditions (concentrations = 1 M, and P = 1 atm), the standard Gibbs energy variation (AG°) is related with the equilibrium constant (A) by equation 11 ... 

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