Equilibrium Properties of Electrolytes

MICROSCOPIC APPROACH TO EQUILIBRIUM AND NON-EQUILIBRIUM PROPERTIES OF ELECTROLYTES... 

Metallic Solutions, Thermodynamics of (Oriani) Microscopic Approach to Equilibrium and Non-Equilibrium Properties of Electrolytes (Resibois and Hasselle-Schuermans). ... 

Electron Systems (Hartmann). Non-Equilibrium and Equilibrium Properties of Electrolytes, Microscopic Approach to (Rfeibois and Hasselle- 5 1... 

Microscopic Approach to Equilibrium and Non-Equilibrium Properties of Electrolytes... 

King, E. J. "Acid-Base Equilibria in "The International Encyclopedia of Physical Chemistry and Chemical Physics Topic 15, Equilibrium Properties of Electrolyte Solutions" Vol. 4, Robinson, R. A., Ed., Pergamon Press, 1965 (distributed by The MacMillan Co., New York). ... 

In recent years we have undertaken a systematic investigation of the volumes and heat capacities of transfer of alkali halides and tetraalkylammonium bromides from water to mixed aqueous solvents (1-6). These properties are important because, when combined with enthalpies and free energies, they can be used to calculate the temperature and pressure dependences of various equilibrium properties of electrolytes in mixed solvents. Since the properties of electrolytes in mixed aqueous solvents are closely related to the corresponding properties of the nonelectrolyte in an electrolyte solution, infor-... 

Attention should be drawn to the fact that there has been a degree of inconsistency in the treatments of ionic clouds (Chapter 3) and the elementary theory of ionic drift (Section 4.4.2). When the ion atmosphere was described, the central ion was considered—from a time-averaged point of view—at rest. To the extent that one seeks to interpret the equilibrium properties of electrolytic solutions, this picture of a static central ion is quite reasonable. This is because in the absence of a spatially directed field acting on the ions, the only ionic motion to be considered is random walk, the characteristic of which is that the mean distance traveled by an ion (not the mean square distance see Section 4.2.5) is zero. The central ion can therefore be considered to remain where it is, i.e., to be at rest. 

As can be seen from the above development, study of the transport properties of electrolyte solutions led scientists in the late nineteenth and early twentieth centuries to think about these systems on a microscopic scale. Important cormec-tions between the movement of ions under the influence of thermal and electrical effects were made by Einstein. This was all brought together in an elegant way by Onsager. An important question faced by those involved with these studies is whether the electrolyte is completely dissociated or not. The answer to this question can be found be examining both the equilibrium and non-equilibrium properties of electrolyte solutions. The latter aspect turns out to be more revealing and is discussed in more detail in the following section. 

The Debye-Hiickel theory discusses equilibrium properties of electrolyte solutions and allows the calculation of an activity coefficient for an individual ion, or equivalently, the mean activity coefficient of the electrolyte. Fundamental concepts of the Debye-Hiickel theory also form the basis of modern theories describing the non-equilibrium properties of electrolyte solutions such as diffusion and conductance. The Debye-Huckel theory is thus central to all theoretical approaches to electrolyte solutions. 

The Debye-Hiickel theory is a study of the equilibrium properties of electrolyte solutions, where departures from ideal behaviour are considered to be a result of coulombic interactions between ions in an equilibrium situation. It is for this reason that equilibrium statistical mechanics can be used to calculate an equilibrium Maxwell-Boltzmann distribution of ions. 

Since ionic association is an electrostatic effect for equilibrium properties of electrolyte solutions, it may be included in the Debye-Hiickel type of treatment by explicitly retaining further terms in the expansion of the Poisson-Boltzmann relation eqn. 5.2.8. - A similar calculation was attempted for conductance by Fuoss and Onsager. The mathematical approach and the model employed are similar to those used in their previous calculation, but they keep explicitly the exp (—0 y) term in the new calculation. The equation derived for A is... 

H. S. Harned and R. A. Robinson, Equilibrium Properties of Electrolyte Solutions Vol. 2, Multicomponent Electrolyte Solutions , Pergamon Press, Oxford, 1968. 

The use of the HNC approximation to study the equilibrium properties of electrolytes and polar fluids is now widespread. Recent examples are the investigations of multipolar fluids by Fries and Patey (1985), the study of the TIPS (transferable intermolecular potentials) model for water and alkali halides in water by Pettitt and Rossky (1982, 1986), and a central-force model for water by Thuraisingham and Friedman (1983). Studies of the rod-like polyelectrolytes (Bacquet and Rossky, 1984) using the HNC approximation have shown qualitative agreement with Manning s (1969, 1978) counter-ion condensation theory, but some quantitative predictions of the theory are not borne out. In the section on WEAK ELECTROLYTES AND DIPOLAR DUMBBELLS, we discuss the sticky electrolyte model for weak electrolytes and acids, which has also been solved numerically in the HNC approximation (Rasaiah and Lee, 1985a). 

Among all possible dynamical and kinetic applications of the cluster densities analysis, it should be noticed that cluster approach can also be fruitful for the study of static and equilibrium properties of electrolyte solutions. 

After 1997, other pseudolattice approaches to equilibrium properties of electrolyte solutions deserve some comment. Moggia and Bianco (Moggia Bianco, 2007 Moggia, 2008) provided expressions for the activity and osmotic coefficients following a pseudolattice approach. The authors assumed that the solute ions evolve from a disordered lattice model within a continuous solvent at extremely dilute solutions to a disordered lattice of local arrangements of both solute ions and solvent dipoles at higher concentrations, and they were able to satisfactorily explain the thermodynamic properties of these systems. 

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