Thermodynamic properties solubility

Mineral Composition Molecular mass, g-mole Equilibrium constant Solubility Thermodynamic properties at, 298,15 K, kj-mole ... 

CHEOPS is based on the method of atomic constants, which uses atom contributions and an anharmonic oscillator model. Unlike other similar programs, this allows the prediction of polymer network and copolymer properties. A list of 39 properties could be computed. These include permeability, solubility, thermodynamic, microscopic, physical and optical properties. It also predicts the temperature dependence of some of the properties. The program supports common organic functionality as well as halides. As, B, P, Pb, S, Si, and Sn. Files can be saved with individual structures or a database of structures. 

The solubilities of Li, Na, and Ca hypochlorites in H2O at 25°C ate 40, 45, and 21%, respectively. Solubility isotherms in water at 10°C have been determined for the following systems Ca(OCl)2—CaCl2, NaOCl—NaCl, and Ca(OCl)2—NaOCl (141). The densities of approximately equimolar solutions of NaOCl and NaCl ate given in several product bulletins (142). The uv absorption spectmm of C10 shows a maximum at 292 nm with a molar absorptivity of 350 cm ( 5)- Heats of formation of alkali and alkaline earth hypochlorites ate given (143). Thermodynamic properties of the hypochlorite ion ate ... 

The acid-base classificationd l turns essentially on the thermodynamic properties of hydroxides in aqueous solution, since oxides themselves are not soluble as such (p. 630). Oxides may be ... 

In this section, we first discuss various experimental techniques that can be used to measure gas solubilities and related thermodynamic properties in ILs. We then describe the somewhat limited data currently available on gas solubilities in ILs. Finally, we discuss the impact that gas solubilities in ILs have on the applications described above (reactions, gas separations, separation of solutes from ILs) and draw some conclusions. 

In this section we describe some of the various experimental techniques that can be used to measure gas solubilities and related thermodynamic properties. 

Individual liquids and elastomers each possess their own solubility parameter, 5. This is a thermodynamic property which is related to the energy of attraction between molecules. In its simplest form, an elastomer will possess a drive to absorb a liquid of similar 8, and be swollen by it. As the difference between the solubility parameter values of species increases, so their affinity for each other decreases. The commonest units for 8 in the literature are (cal cm ) / to convert values thus to MPa, multiply by 2.05. 

Thermodynamic Properties The variation in solvent strength of a SCF from gaslike to liquidlike values (see Table 20-12) may be described qualitatively in terms of the density p, as shown in Fig. 20-17, or the solubility parameter. 

Langmuir, D., Techniques of estimating thermodynamic properties for some aqueous complexes of geochemical interest, in Chemical Modeling in Aqueous Systems Speciation, Sorption, Solubility and Kinetics, Jenne, E.A., Ed., ACS Symposium, American Chemical Society, Washington, DC, 1979, pp. 353-387. 

Permeability (P) is usually defined as the product of a thermodynamic property and a transport property which are, respectively, the partition or solubility coefficient, K, and the diffusion coefficient, D. This partition coefficient is defined as the ratio at equilibrium of the solute concentration inside the gel to that in solution. A value of K less than 1 indicates that the solute favors the solution... 

Meyer RE, Arnold WD, Case FI, O Kelly GD (1988) Thermodynamic properties of Tc(IV) oxides solubilities and the electrode potential of the Tc(VII)/Tc(IV) oxides couple NUREG/CR-5108 ORNL-6480... 

A large number of compounds of pharmaceutical interest are capable of being crystallized in either more than one crystal lattice structure (polymorphs), with solvent molecules included in the crystal lattice (solvates), or in crystal lattices that combine the two characteristics (polymorphic solvates) [122,123]. A wide variety of structural explanations can account for the range of observed phenomena, as has been discussed in detail [124,125]. The pharmaceutical implications of polymorphism and solvate formation have been recognized for some time, with solubility, melting point, density, hardness, crystal shape, optical and electrical properties, vapor pressure, and virtually all the thermodynamic properties being known to vary with the differences in physical form [126]. 

Before considering different theoretical approaches to determining the free energies and other thermodynamic properties of ionic solvation, it is important to be aware of a problem on the experimental level. There are several methods available for obtaining these quantities for electrolyte solutions, both aqueous and nonaqueous some of these have been described by Conway and Bockris162 and by Padova.163 For example, enthalpies of solvation can be found via thermodynamic cycles, free energies from solubilities or galvanic cell potentials. However the results... 

By examining the compositional dependence of the equilibrium constant, the thermodynamic properties of the solid solution can be determined if the final solution is either at equilibrium or stoichiometric saturation. That is, the provisional activities and activity coefficients will be valid if either equilibrium or stoichiometric saturation is attained in the solubility data. 

Most thermodynamic data for solid solutions derived from relatively low-temperature solubility (equilibration) studies have depended on the assumption that equilibrium was experimentally established. Thorstenson and Plummer (10) pointed out that if the experimental data are at equilibrium they are also at stoichiometric saturation. Therefore, through an application of the Gibbs-Duhem equation to the compositional dependence of the equilibrium constant, it is possible to determine independently if equilibrium has been established. No other compositional property of experimental solid solution-aqueous solution equilibria provides an independent test for equilibrium. If equilibrium is demonstrated, the thermodynamic properties of the solid solution are also... 

In application of this method to solubility data (8) in the KCl-KBr- O system at 25°C, it is found that equilibrium is in general not attained, though some mid-range compositions may be near equilibrium. As the highly soluble salts are expected to reach equilibrium most easily, considerable caution should be exercised before reaching the conclusion that equilibrium is established in other low-temperature solid solution-aqueous solution systems. It is not appropriate to derive thermodynamic properties of solid solutions from experimental distribution coefficients unless it can be demonstrated that equilibrium has been attained. 

It is shown that the properties of fully ionized aqueous electrolyte systems can be represented by relatively simple equations over wide ranges of composition. There are only a few systems for which data are available over the full range to fused salt. A simple equation commonly used for nonelectrolytes fits the measured vapor pressure of water reasonably well and further refinements are clearly possible. Over the somewhat more limited composition range up to saturation of typical salts such as NaCl, the equations representing thermodynamic properties with a Debye-Hiickel term plus second and third virial coefficients are very successful and these coefficients are known for nearly 300 electrolytes at room temperature. These same equations effectively predict the properties of mixed electrolytes. A stringent test is offered by the calculation of the solubility relationships of the system Na-K-Mg-Ca-Cl-SO - O and the calculated results of Harvie and Weare show excellent agreement with experiment. 

Walther J. V. and Helgeson H. C. (1977). Calculation of the thermodynamic properties of aqueous silica and the solubility of quartz and its polymorphs at high pressures and temperatures. Amer. Jour. Set, 277 1315-1351. 

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