Calculation of the thermodynamic and transport properties of aqueous species at high pressures and temperatures: Correlation algorithms for ionic species and equation of state predictions to 5 kb and 1000°C

Calculation of the thermodynamic and transport properties of aqueous species at high pressures and temperatures: Standard partial molal properties of organic species

A Thermodynamic Model of the System HCl-HNO3-H2SO4-H2O, Including Solubilities of HBr, from <200 to 328 K

The enthalpies of solution of urea (U) in water (W)-tert-butanol (TBA) mixtures and of TBA in W-U mixtures, the enthalpies of dilution of TBA in W, and the enthalpies of mixing of U and TBA aqueous solutions were measured with a solution calorimeter and a flow microcalorimeter. Enthalpies of transfer of U and TBA to the mixed solvents were derived. Also, pair and triplet interaction parameters between the various solutes were derived from the mixing and dilution experiments. The enthalpic pair parameter hU-TBA is positive, suggesting that the main contribution to this parameter is the decrease in hydrophobic hydration of TBA in the presence of U.

Enthalpies of the urea-tert-butanol-water system at 25°C

A new model for calculating the viscosity of aqueous solutions has been developed. Parameters for 74 solutes were established based on a critical review of the literature for solutions of one solute in water, with over 9000 points included. The average difference between the calculated and experimental viscosities is less than 0.1 %, and the standard deviation of this difference is 3.7 % of the average experimental viscosity. The model was validated by estimating published viscosity for systems of more than one solute in water. The average difference between experimental and calculated values for 1700 points is −2.7 %, and the standard deviation of this difference is 16 % of the average experimental viscosity. The median standard deviation of the difference between experimental and calculated values is 3.5 % of the experimental viscosity. The solutes studied are (NH4)2SO4, AlCl3, BaCl2, Ca(NO3)2, CaCl2, Cd(NO3)2, CdCl2, CdSO4, CoCl2, CoSO4, Cr2(SO4)3, CrCl3, Cu(NO3)2, CuCl2, CuSO4, Fe2(SO4)3, FeCl2, FeSO4...

Model for Calculating the Viscosity of Aqueous Solutions

The enthalpies of dilution and volumetric specific heats of most alkali halides were measured in water at 25°C with flow microcalorimeters in the concentration range 0.01 to 1m. Apparent molal relative enthalpiesφ
L, derived from the enthalpies of dilution, can be represented by a parametric equation in molality. Combiningφ
L with osmotic data, excess entropies can be calculated. Excess free energies, enthalpies, and entropies are compared at 0.5m, and the observed trends are consistent with a model of structural interactions in aqueous alkali halide solutions. The apparent molal heat capacitiesφ
C were fitted with the equationφ
C=φ

 C
 °
 +AC(d0m)1/2+B
 C
 m. Theφ

 C
 °
 are, in general, additive to better than 1 J-K−1-mole−1 and reflect mostly the structural part of ion-solvent interactions. Takingφ

 C
 °
 (H+)=0, conventional ionicφ

 C
 °
 are obtained. The parameterB

 C
 for different pairs of ions follows approximately the same trends as the corresponding parameterB

 V
 for apparent molal volumes and seems to reflect structural interactions between the ions.

Thermodynamic properties of alkali halides. II. Enthalpies of dilution and heat capacities in water at 25°C

The apparent molar heat capacities and volumes of aqueous NaCl from 0.01 to 3 mol kg−1 in the temperature range 274.65 to 318.15 K

The aqueous sedimentation behavior of commercial chrysotile asbestos fibers has been investigated and a simple method for separating short fibers (90% < 2 μm) could be devised based on selective sedimentation. Chemical, X-ray structural, and differential thermal analyses show that the short fibers have chrysotile composition and structure, with lower brucite (Mg(OH)2) and iron contents than the bulk fibers. The length distribution of these short fibers exhibits a maximum at 0.3 μm and a width-at-half-height of ∼0.5 μm. Surface adsorption studies yield specific areas of 20 and 28 m2/g for N2 and H2O respectively. Because of their finely divided state and narrow length distribution, such fibers should be well suited for a variety of physico-chemical, chemical, and biological investigations on chrysotile fibers.

Separation of short fibers from bulk chrysotile asbestos fiber materials: analysis and physico-chemical characterization.

The enthalpies of dilution of NaCl, Me4NBr, andn-Bu4NBr were measured in water at 25°C with a new flow microcalorimeter. The data were analyzed with a polynomial equation, and the derived relative apparent molal enthalpies φL are in good agreement with literature values. Provided care is taken that mixing is complete, flow calorimeters are as reliable and much less time-consuming than cell-type instruments for enthalpies of dilution measurements.

Enthalpies of dilution of electrolyte solutions by flow microcalorimetry

The volumetric specific heats and densities of alkali fluorides, alkali bromides, and soduum halides were measured in D2O at 25°C in the concentration range 0.05 to 1 aquamolal. The results can be combined with data in H2O to give the corresponding standard and excess transfer functions from H2O to D2O. The volumes and heat capacities of transfer are both negative but, contrary to the hydration functions, show little dependence on ionic size and sign. Also, while heats, entropies, and volumes of transfer are usually small compared with the hydration functions, the heat capacity of transfer is of comparable magnitude. These observations, when interpreted with the Frank and Wen model, suggest that the total number of water molecules in the hydration cosphere is approximately constant for all alkali halides and that heat capacities are more sensitive to structural interactions than volumes and enthalpies. The sign of the excess transfer functions is consistent with the presence of structural ion-ion interactions, but no systematic trend with ionic size can be detected in view of the large experimental uncertainty.

Jean-Luc Fortier

Papers

Thermodynamic properties of alkali halides. II. Enthalpies of dilution and heat capacities in water at 25°C

The apparent molar heat capacities and volumes of aqueous NaCl from 0.01 to 3 mol kg−1 in the temperature range 274.65 to 318.15 K

Separation of short fibers from bulk chrysotile asbestos fiber materials: analysis and physico-chemical characterization.

Enthalpies of dilution of electrolyte solutions by flow microcalorimetry

Thermodynamic properties of alkali halides. III. Volumes and heat capacities of transfer from H 2 O to D 2 O at 25°C