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Energy and activity coefficients

Figure 12.22 Plots showing the excess Gibbs energy and activity coefficients based on the as treatment of solution ideality. Figure 12.22 Plots showing the excess Gibbs energy and activity coefficients based on the as treatment of solution ideality.
The curves in Figs. 13.18 and 13.19 provide an excellent correlation c VLE data. They result from BUBL P calculations carried out as indicated in 12.12. The excess Gibbs energy and activity coefficients are here express functions of liquid-phase composition by the 4-parameter modified, Ma... [Pg.242]

Since this temperature is still well below the melting points of the species, our conclusion does not change, there is no phase separation. We do, however, see the importance of accounting for the temperature dependence of the excess Gibbs free energy (and activity coefficients) ]... [Pg.389]

Of more interest are solubility calculations in the ternary system NaCl-KCl-H20. The equations for the excess Gibbs energy and activity coefficients in a mixture of a solvent and two salts with a common ion, MX and NX, and with cation fraction F of M are given by Pitzer and Simonson (5). Their equation for the activity coefficient of the solute MX in the ternary mixture MX-NX-H2O based on a pure fused salt standard state can be converted to one based on the infinitely dilute reference state. This is given by ... [Pg.52]

Excess Gibbs free energy and activity coefficients... [Pg.191]

Excess Gibbs energy and activity coefficients are linked. From the equations (6.30) and (6.33) the following fundamental relation is obtained ... [Pg.191]

The partial molar excess Gibbs energy of a solute in hquid Cd represents the interaction between the solute and liquid Cd. The relation between the partial molar excess Gibbs energy and activity coefficient (y) in liquid Cd is given as ... [Pg.502]

EXCESS GIBBS ENERGY AND ACTIVITY COEFFICIENT EQUATIONS... [Pg.148]

An overview of some basic mathematical techniques for data correlation is to be found herein together with background on several types of physical property correlating techniques and a road map for the use of selected methods. Methods are presented for the correlation of observed experimental data to physical properties such as critical properties, normal boiling point, molar volume, vapor pressure, heats of vaporization and fusion, heat capacity, surface tension, viscosity, thermal conductivity, acentric factor, flammability limits, enthalpy of formation, Gibbs energy, entropy, activity coefficients, Henry s constant, octanol—water partition coefficients, diffusion coefficients, virial coefficients, chemical reactivity, and toxicological parameters. [Pg.232]

By combining these ions with other counterions, single ion transfer activity coefficients are calculated. By these techniques transfer free energies or activity coefficients have been determined for many ions and nonelectrolytes in a wide variety of solvents.Parker has discussed the extrathermodynamic assumptions that lead to single ion quantities. [Pg.420]

Reactions in solution proceed in a similar manner, by elementary steps, to those in the gas phase. Many of the concepts, such as reaction coordinates and energy barriers, are the same. The two theories for elementary reactions have also been extended to liquid-phase reactions. The TST naturally extends to the liquid phase, since the transition state is treated as a thermodynamic entity. Features not present in gas-phase reactions, such as solvent effects and activity coefficients of ionic species in polar media, are treated as for stable species. Molecules in a liquid are in an almost constant state of collision so that the collision-based rate theories require modification to be used quantitatively. The energy distributions in the jostling motion in a liquid are similar to those in gas-phase collisions, but any reaction trajectory is modified by interaction with neighboring molecules. Furthermore, the frequency with which reaction partners approach each other is governed by diffusion rather than by random collisions, and, once together, multiple encounters between a reactant pair occur in this molecular traffic jam. This can modify the rate constants for individual reaction steps significantly. Thus, several aspects of reaction in a condensed phase differ from those in the gas phase ... [Pg.146]

All quantities in Eq. (12.6) are measurable The concentrations can be determined by titration, and the combination of chemical potentials in the exponent is the standard Gibbs energy of transfer of the salt, which is measurable, just like the mean ionic activity coefficients, because they refer to an uncharged species. In contrast, the difference in the inner potential is not measurable, and neither are the individual ionic chemical potentials and activity coefficients that appear on the right-hand side of Eq. (12.3). [Pg.156]

This property simply considered is the first temperature derivative of the free energy or activity and can be used to obtain osmotic coefficients and activity coefficients by the relationships ... [Pg.570]

The term (a, /xi) is called the activity coefficient. Methods of measuring the activity and activity coefficient are given in Chapter 5. Tabulations of Gibbs energies of mixing of numerous systems defined in various ways are available in standard reference books, such as Hultgren et al. (1973) and Kubaschewski et al. (1993). [Pg.67]

Hence, ArG° is a measure of the free energy of the reaction when all species are present in their standard state (where concentrations are assumed to be 1 M, and activity coefficients are set to 1). We should recall that a negative ArG0 would mean that, under standard conditions, the reaction Eq. 12-1 would proceed spontaneously from left to right if ArG0 is positive, the reaction would proceed spontaneously in the opposite direction. [Pg.464]

Refs 51, 53 58) reviewed the data of Warren gt oi (Ref 37) and observed that a few nonrigid generalizations could be made. Although the materials can be ordered relative to decompn. a variation in kinetics as shown by the calcns for the activation energies and temp coefficients of evaluation as follows ... [Pg.53]

Lord and Pritchard34 found that when the iodinolysis of dimethylmercury was carried out with rigorous exclusion of light, the reaction was first-order in dimethylmercury and first-order in iodine. Activation energies and rate coefficients for iodinolysis of dimethylmercury in a number of solvents were determined. For solvent carbon tetrachloride, the second-order rate coefficient at 28 °C was found to be 0.073 l.mole-1.min-1 and Ea = 7.7 kcal.mole-1. The corresponding values of Razuvaev and Savitskii33 are k2 = 0.11 l.moIe-1.min-1 and Ea = 9.5 kcal. mole-1. ... [Pg.160]

Free energies of formation and activity coefficients of the relevant sulfur moieties at the prevailing temperature or—alternatively—formal potentials of the corresponding redox couples. [Pg.423]

The -> concentration cells are used only for determination of -> transport (transference) numbers, - activity, and -> activity coefficients of electrolytes and other quantities. Their practical application is limited by the -> selfdischarge due to the spontaneous diffusion process. In concentration cells no chemical reactions occur, a physical process (the equalization of activities by diffusion) causes the potential difference and supplies the energy. [Pg.290]

Cmp and Dmp are specific constants related to the dimensions of the macromolecule, while the coefficient Amp is inversely dependent on protein size. A similar relationship can be derived for the stationary phase component of the change in the Gibbs free energy due to electrostatic effects (AG >sp><), although the precise relationship between salt concentration in the mobile phase and activity coefficient of the protein when bound to the sorbent may take a more complex form. The electrostatic free-energy change associated with the chromatographic retention process then can be expressed as... [Pg.123]

ACTIVITY AND ACTIVITY COEFFICIENTS In our deduction of the law of mass action we used the concentrations of species as variables, and deduced that the value of the equilibrium constant is independent of the concentrations themselves. More thorough investigations however showed that this statement is only approximately true for dilute solutions (the approximation being the better, the more dilute are the solutions), and in more concentrated solutions it is not correct at all. Similar discrepancies arise when other thermodynamic quantities, notably electrode potentials or chemical free energies are dealt with. To overcome these difficulties, and still to retain the simple expressions derived for such quantities, G. N. Lewis introduced a new thermodynamic quantity, termed activity, which when applied instead of concentrations in these thermodynamic functions, provides an exact fit with experimental results. This quantity has the same dimensions as concentration. The activity, aA, of a species A is proportional to its actual concentration [A], and can be expressed as... [Pg.22]


See other pages where Energy and activity coefficients is mentioned: [Pg.252]    [Pg.252]    [Pg.409]    [Pg.532]    [Pg.553]    [Pg.252]    [Pg.112]    [Pg.81]    [Pg.252]    [Pg.252]    [Pg.409]    [Pg.532]    [Pg.553]    [Pg.252]    [Pg.112]    [Pg.81]    [Pg.512]    [Pg.834]    [Pg.323]    [Pg.87]    [Pg.274]    [Pg.162]    [Pg.78]    [Pg.59]    [Pg.42]    [Pg.286]    [Pg.128]   
See also in sourсe #XX -- [ Pg.23 ]




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