Calculation of Gibbs free energies of aqueous electrolytes to 350.degree.C from an electrostatic model for ionic hydration

Abstract

Publication costs assisted by Atomic Energy of Canada Limited An electrostatic model that had previously been developed to describe standard state thermodynamic functions for ionic hydration at 298 K is used to calculate the Gibbs free energy function, G°T -G°298, for 14 group la, 2a, 3a, and 3b cations and the trivalent lanathides and actinides, from 323 to 623 K. The calculation employs a temperature independent primary hydration number derived from the entropy of each aquo ion at 298 K as the only adjustable parameter. Above 423 K, the standard state partial molal Gibbs free energies predicted by the model reproduce the available experimental data much more accurately than those calculated by the Criss-Cobble entropy correspondence principle or by assuming that the room temperature heat capacities are invariant with temperature. Results from the model are less reliable above 548 K, presumably because of compressibility effects and variations in the primary hydration number.

Predicting Solubility of Oxides of Metals and Metalloids in Supercritical Water

“…The question is the prediction of the parameter n ( T ). In order to roughly estimate it, one can use the following reasoning: as is known, − the Gibbs energy of transfer, Δ tr G o , of a molecule between coexisting phases contains the term proportional to the logarithm of densities of these phases. In the case of a transfer of one molecule from an ideal gas (g) at the standard-state pressure P ⌀ to water at the pressure P , this gives the following term: …”

Complexation between polyallylammonium cations and polystyrenesulfonate anions: the effect of ionic strength and the electrolyte type

“…In contrast, the anion hydration becomes slightly more favourable as water temperature increases. 61 Weak temperature dependence of polyelectrolyte osmotic coefficients 62 indicates that these two opposing effects largely cancel each other. Consequently, the process should be quite favourable in terms of entropy even at high temperatures.…”

Uranium and plutonium equilibriums in aqueous solutions to 200.degree.C

“…Although C°(T) data are known for the uranium and plutonium solids, and several of their complexation reactions, no values have been reported for any of the aqueous species. Several methods for estimating such data have been proposed (13,(102)(103)(104)(105). The most widely used method which can be applied to polyatomic species is the Criss-Cobble entropy correspondence principle (13,14).…”