The Physical Chemistry of Electrolytic Solutions.

A large number of quantitative studies have been made of the Gibbs energy of transfer (the solvent medium effect) for cations transferring from water into mixed aqueous−organic solvent systems, mainly at 25 °C. Nevertheless, no systematic effort appears to have been made to compile and analyze these data, particularly for multivalent cations. A critical review of this information and its presentation in a manner that permits comparison of different cations in a given solvent mixture and of a given cation transferring into different mixtures is therefore of value.

Gibbs energies of transfer of anions from water to mixed aqueous organic solvents.

A wide-ranging critically evaluated compilation of the standard molar enthalpies and entropies of transfer of electrolytes from water to mixed aqueous-organic solvents were shown. For this compilation, the reported values were recalculated to obtain a consistent format that enabled comparisons to be made among the data. These whole-salt data were then split into the transfer functions of the individual ions, using an appropriate extrathermodynamic assumption.

Enthalpies and Entropies of Transfer of Electrolytes and Ions from Water to Mixed Aqueous Organic Solvents

Solutions properties and solute-solvent interactions in ternary sugar-salt-water solutions

Viscosity of sugar solutions is informative on the transport properties of the sucrose molecule in the aqueous medium. For this reason, it is a physical property particularly important in crystallization studies. Viscosity is affected by temperature, concentration of solute and of suspended matter. Slight amounts of impurities, especially macromolecules, provoke an appreciable increase in viscosity and a change in the rheological behaviour of concentrated sucrose solutions. As stressed in an earlier review (Mathlouthi and Kasprzyk, 1984) theory is a good guide to practice and the solving of the day-to-day problems posed in a sugar factory such as the flow in pipes, cooling of crystallizers, centrifugation or molasses exhaustion, require that rheological properties of syrups, molasses and massecuites be taken into account.

Rheological properties of sucrose solutions and suspensions

Electromotive force measurements of the cell Pt, H2/HBr(m), dioxan(X) H2O(Y)/AgBr/Ag have been made at 15, 25, 35 and 45°C for solvent compositions X= 10, 20, 30, 40, 60 %(w/w) of dioxan. These have been used to evaluate the standard potentials of the cell, the mean activity coefficient of HBr (molal scale) and the thermodynamic functions (mole-fraction scale) for the transfer of HBr from water to the respective dioxan + water media. The ΔG°t(free energy of transfer of the acid from water to various solvents) values along with those for hydrochloric acid, are briefly discussed in relation to ion solvation.

Thermodynamics of hydrobromic acid in dioxan + water mixtures from electromotive force measurements at different temperatures

The thermodynamics of the potassium chloride—water—sucrose system from viscosity studies

Thermodynamic studies of hydrogen iodide in dioxane-water mixtures from electromotive force measurements

The free enrgies of transfer (ΔG t 0 ) of H+, Cl−, Br−, I− and SCN− ions from water to 10, 20, 30 and 40% dioxanewater mixtures have been studied from potentiometric measurements. For anions the ΔG t 0 values are in the order Cl−>Br−>SCN−>I−.

Bijoy K. Das

Papers

Thermodynamics of hydrobromic acid in dioxan + water mixtures from electromotive force measurements at different temperatures

The thermodynamics of the potassium chloride—water—sucrose system from viscosity studies

Thermodynamic studies of hydrogen iodide in dioxane-water mixtures from electromotive force measurements

Studies on hydrogen, halides and thiocyanate ions in dioxane-water mixtures at various temperatures

Thermodynamic studies with silver—silver thiocyanate electrodes: transfer of (H+ SCN−) from aqueous to dioxane—water solutions