Osmotic Coefficients and Activity Coefficients of Nonaqueous Electrolyte Solutions. Part 2. Lithium Perchlorate in the Aprotic Solvents Acetone, Acetonitrile, Dimethoxyethane, and Dimethylcarbonate

Vapor pressure lowering by the addition of lithium perchlorate to the aprotic solvents acetone (0.02–0.6 m), acetonitrile (0.05–1.2 m), dimethoxyethane (0.02–0.4 m), and dimethylcarbonate (0.03–1.8 m) was measured at 25°C with high precision. The experimental data for the corresponding osmotic coefficients are compared to those obtained from the Pitzer equations and chemical model calculations. Mean activity coefficients are derived from the osmotic coefficients.     

Osmotic Coefficients and Activity Coefficients of Nonaqueous Electrolyte Solutions. Part 4. Lithium Bromide, Tetrabutylammonium Bromide, and Tetrabutylammonium Perchlorate in Acetone

Vapor pressure lowering by the addition of lithium bromide (0.03–0.8m), tetrabutylammonium bromide (0.01–0.8m), and tetrabutylammonium perchlorate (0.02–3.6m) to acetone was measured at 25°C with high precision. The experimental data of the corresponding osmotic coefficients are compared to those obtained by the use of Pitzer equations and chemical model calculations. Mean activity coefficients are derived from the osmotic coefficients.     

Osmotic Coefficients and Activity Coefficients of Nonaqueous Electrolyte Solutions. Part 3. Tetraalkylammonium Bromides in Ethanol and 2-Propanol

Vapor pressure lowering by the addition of tetraethylammonium bromide (0.04 to 2.3 m), tetrapropylammonium bromide (0.04–2.7 m), tetrabutylammonium bromide (0.05–2.5 m), bispiperidinium bromide (0.04–0.7 m) to ethanol and tetrapropylammonium bromide (0.04–1.3 m) and tetrabutylammonium bromide (0.03–1.9 m) to 2-propanol was measured at 25°C with high precision. The experimental data of the corresponding osmotic coefficients are compared to those obtained by the use of Pitzer equations and chemical model calculations. Mean activity coefficients are derived from the osmotic coefficients.     

Thermodynamics of mixed electrolyte solutions. IX. Calculation of the osmotic and activity coefficients in a pseudoternary system (NaCl−nKCl)−MgCl2-H2O at 298.15°K

The equation of Reilly, Wood, and Robinson was used to predict the osmotic coefficient of a pseudoternary system (NaCl–nKCl)–MgCl₂–H₂O over a molal ionic strength range of 1.0 to 5.0 moles-kg^–1. The results are in close agreement with experimental data at most ionic strengths. The standard deviation in the osmotic coefficients over the entire concentration range lies within 0.0035. The predicted values of the mean activity coefficients are in good agreement with those obtained by the treatments of both Scatchard and Friedman. Mean activity coefficients for the other components were also predicted.     

Hygrometric Determination of Water Activities, Osmotic and Activity Coefficients, and Excess Gibbs Energy of the System MgSO4–K2SO4–H2O

Ternary aqueous solutions of MgSO₄ and K₂SO₄ have been studied by the hygrometric method at 25°C. The relative humidity of this system is measured at total molalities from 0.35 mol-kg^–1 to about saturation for three ionic-strength fractions (y = 0.25, 0.50, and 0.80 of MgSO₄. The data allow calculation of water activities and osmotic coefficients. From these measurements, the Pitzer ionic mixing parameters are determined and used to predict the solute activity coefficients in the mixture. The results are used to calculate the excess Gibbs energy at total molalities for ionic-strength fraction y.     

Equilibrium isotope effects in aqueous systems. IV. The vapor pressures of NaBr,Nal, KF,Na2SO4, and CaCl2 solutions in H2O and D2O (O to 90°C). Vapor pressures of Na2SO4·10H2O, ·10D2O and CaCl2·2H2O, ·2D2O

Solvent vapor pressure isotope effects have been measured in HOH/DOD between approximately 0 and 90°C on the following electrolyte solutions: NaBr (2, 5, 7, and 9m), NaI (4, 6, 8, and 10m), KF (3, 6, 9, and 12m), Na₂SO₄ (2m and saturated solutions, and hydrated cyrstal), and CaCl₂ (3, 5.5, 8, and 10m, and hydrated crystal). Values of the isotope effects on the various excess thermodynamic properties of solution, including the osmotic and activity coefficients and the excess free energies, enthalpies, and entropies, have been extracted from least-square expressions which fit the VPIE over the entire concentration and temperature range. The results are compared with those obtained for alkali metal chloride solutions (I, II) and literature data where possible. They are discussed briefly in terms of solution structure.     

Equilibrium and Transport Properties of Sodium n-Octyl Sulfonate Aqueous Solutions

Measurements of osmotic coefficients, mutual diffusion coefficients, and conductivity were performed on the binary system sodium n-octyl sulfonate (C₈SO₃Na)–water at 25°C both below and above the micellar composition range. The osmotic coefficient data were obtained through vapor-pressure osmometry, while the Taylor dispersion method was used to measure diffusion coefficients. The mass equilibrium model was applied to this self-aggregating system, taking into account the deviation of the activity coefficients from the Debye–Hückel limiting law by using the Guggenheim corrective terms for mixed electrolyte solutions. The expressions derived from the model fit the experimental osmotic and diffusion coefficient data well, when the same values of aggregation number, fraction of condensed counterions, and equilibrium constant are used. Osmotic coefficients were also used to determine the thermodynamic factor required to compute the solute mobility from diffusion data. Conductivity data were used to test two theoretical models, namely, the Onsager–Fuoss and the Mean Spherical Approximation theories. Both models have been found to yield unsatisfactory fits to our experimental data and some arbitrary terms had to be applied to the theoretical expressions to obtain good agreement between experiment and theory.     

Semi-empirically derived petrophysical and thermodynamical coefficients of permselective shales—Implications on ore mineralization

Phenomenological coefficients of shale–electrolyte systems may offer a glimpse into probable matrix-permeability and solute-exclusionary relationships. Shales from unexposed Upper Cretaceous Period Mancos Shale and from Permian Period Abo Formation were cut into thin wafers, placed in custom built osmometers and a chemical potential applied across them giving rise to induced osmotic flow. This in turn spawned matrix unique constants namely mechanical filtration coefficient L_P (m³ N⁻¹ s⁻¹), diffusional mobility per unit osmotic pressure L_PD (m³ N⁻¹ s⁻¹), osmotic flow coefficient; L_D (m³ N⁻¹ s⁻¹), reflection coefficient σ (dimensionless) at zero gradients of temperature and hydrostatic pressure. Considering intrinsic relationships between these constants where and L_PD = −σL_P, we have ascertained that the bentonitic fossiliferous Mancos shale had a lower L_P and a higher σ compared to the kaolinitic and siliceous shale from Abo Formation indicating a higher degree of compaction post-diagenesis (lower porosity) and higher filtration efficiency. Mechanistic processes involved in solute transport and matrix morphology indicate key multi-scale transformations, ionic- and atomic-exchange competitions on high energy sites like cation-exchange sites, isomorphic substitution at argillaceous mineral edges, atomic-clipping within basal spacing, preferential pathway migration, dead-end pores that give rise to localized solute exclusionary processes and solute attenuation giving rise to anomalous osmotic gradients.     

Osmotic and activity coefficients of monomethyl-, dimethyl-, and trimethylammonium chlorides at 25°C

The osmotic and activity coefficients of monomethyl-, dimethyl-, and trimethylammonium chlorides in aqueous solution have been determined at 25°C by the gravimetric isopiestic method. The measurements extend from 0.1 molal (m) to 20, 17, and 15 mol-kg^–1, respectively, for the three salts. In the region below 2m, the osmotic coefficients decrease in the order NH₄Cl>MeH₃NCl>Me₂H₂NCl>Me₃HNCl>Me₄NCl, and above 3m the order is reversed. The intermediate members of the series have identical osmotic coefficients at the crossover molality of 3.0. It is suggested that the behavior at low molalities reflects primarily ion-dipole interactions, decreasing as the cation size increases, whereas hydrophobic (structure-making) interactions, increasing in importance with the number of non-polar methyl substituents, are predominant in concentrated solutions of these salts.     

Hygrometric Determination of Water Activities and Osmotic and Activity Coefficients of NH4Cl–LiCl–H2O at 25°C

The mixed aqueous electrolyte system of ammonium and lithium chlorides has been studied by the hygrometric method at 25°C. The relative humidities of this system are measured at total molalities from 0.3 to 6 mol-kg^{– 1} for different ionic-strength fractions y of NH₄Cl with y = 0.33, 0.50, and 0.67. The data obtained allow the deduction of new water activities and osmotic coefficients. The experimental results are compared with the predictions of the ECA (extended composed additivity) law proposed in our previous work. The Zdanovskii–Stokes–Robinson (ZSR), the Robinson–Stokes (RS), Reilly–Wood–Robinson (RWR), the Pitzer, and the Lietzke–Stoughton (LS II) models are also compared with our results. Predictions made using these models are, in general, consistent with our results. From these measurements, new Pitzer mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture for different ionic-strength fractions.     

The Effect of Anomeric Head Groups, Surfactant Hydrophilicity, and Electrolytes onn-Alkyl Monoglucoside Microemulsions

The effects of the variables of head group structure and salt concentration on microemulsions formed in mixtures of water, alkyl ethylene glycol ethers (C_kOC₂OC_k), andn-alkyl β- -glucopyranosides (C_mβG₁) are explored. Phase behavior of mixtures containing an anomer of the surfactant (n-alkyl α- -glucopyranoside, C_mαG₁), or surfactants with long head groups (n-alkyl maltopyranosides, C_mG₂), or NaCl or NaClO₄as electrolyte are systematically reported as a function of temperature and composition. The substitution ofn-alkyl α- -glucopyranosides forn-alkyl β- -glucopyranosides causes precipitation under some conditions in all mixtures studied. These solubility boundaries begin in the water–surfactant binary mixture at the Krafft boundary, then extend to high concentrations of both surfactant and oil. Increasing the effective length of the surfactant head group by adding C_mG₂to water–C_kOC₂OC_k–C_mβG₁mixtures moves the phase behavior dramatically up in temperature when even small amounts of C_mG₂are used. Adding a lyotropic electrolyte, NaCl, to water–C_kOC₂OC_k–C_mβG₁mixtures moves the phase behavior down in temperature, while the hydrotropic electrolyte NaClO₄moves the phase behavior up in temperature.     

Hygrometric Determination of Water Activities and Osmotic and Activity Coefficients of NH4Cl–KCl–H2O at 25°C

Relative humidities have been measured for mixed aqueous electrolyte system of ammonium and potassium chlorides by the hygrometric method at total molalities from 0.3 to 6 mol-kg^–1for ionic-strength fractions yof NH₄Cl of 1/3, 1/2, and 2/3 at 25°C. The data allow the calculation of new water activities and osmotic coefficients. The proposed ECA (extended composed additivity) rule of calculation of water activity in mixed aqueous electrolyte solutions from the water activities of a single component is extended to this system. The experimental results and the predictions of the ECA rule are compared with the Robinson–Stokes, Reilly–Wood–Robinson, the Pitzer, and the Lietzke–Stoughton II models. Predictions made using these models are, in general, consistent with our results. From these measurements, the Pitzer mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture for different ionic-strength fractions.     

Correlation of Osmotic Coefficient Data for ZnSO4(aq) at 25°C by Various Thermodynamic Models

The available literature data on the osmotic coefficient of ZnSO₄(aq) at 25°C in the molality range from 0.1 to 4.3 mol-kg^–1 and new experimental data from 1.2 to 2.9 mol-kg^–1, at the same temperature, are presented. Selected values of the osmotic coefficient from all the data are analyzed using the Clegg-Pitzer-Brimblecombe model, the extended Pitzer model, and a semiempirical equation comprising a power series in molality added to the Debye-Hückel limiting law. The extended Pitzer equation and the Clegg-Pitzer-Brimblecombe equations give the best results in fitting the osmotic coefficient data. All three models are used to calculate ZnSO₄ activity coefficients at 25°C in dilute solutions (<0.1 mol-kg^–1) for comparison with published values.     

Electromotive-force studies of mixed electrolytes in mixed solvents. HCl+NH4Cl in methanol+water solvents at 25°C

Electromotive-force measurements of the cell Pt, H₂(g, 1 atm)|HCl(m₁), NH₄Cl(m₂), methanol(X%), Water(100–X)%|AgCl|Ag have been made at 25°C for m₁+m₂=1 mole-kg^–1 and X=0, 10, 20, 30, 40, and 50% methanol by weight. Hydrochloric acid obeys Harned's rule in aqueous solutions, but a quadratic term is required in the mixed solvents. The Harned coefficients for the acid vary with solvent composition, and this invalidates the applicability of Harned's method for estimating activity coefficients for single electrolytes in mixed solvents. This method is described and the reason for the inapplicability of the method is discussed in terms of ion-ion and ion-solvent interactions.     

Water Activity and Osmotic Coefficients in Solutions of Glycine,Glutamic Acid,Histidine and their Salts at 298.15 K and 310.15 K

From vapor pressure osmometry data, the activity of water, osmotic coefficients and mean ionic activity coefficients of glycine (m=0.006−3.2 mol⋅kg⁻¹), L-histidine (m=0.005−0.23 mol⋅kg⁻¹), L-histidine monohydrochloride (m=0.008−0.63 mol⋅kg⁻¹), glutamic acid (m=0.004−0.05 mol⋅kg⁻¹), sodium L-glutamate (m=0.007−0.6 mol⋅kg⁻¹), and calcium L-glutamate (m=0.008−0.6 mol⋅kg⁻¹) have been obtained in aqueous solutions at 298.15 and 310.15 K. The Pitzer equations and the mean spherical approximation (MSA) are used for theoretical modeling. The results are supplied as reference thermodynamic material for the characterization of more complex molecules such as proteins.     

Vapor pressure data for non-aqueous electrolyte solutions. Part 5. Tetraalkylammonium salts in acetonitrile

Precise vapor pressure data for solutions of Et₄NBr (concentration range of 0.04–1]<0.4), Pr₄NBr (0.044NBr (0.024NCl (0.044NI (0.054NBr (0.06相似文献   

Taylor dispersion measurements at low electrolyte concentrations. I. Tetraalkylammonium perchlorate aqueous solutions

An equipment for the determination of mutual diffusion coefficients using the Taylor's dispersion technique is described. The radius of the capillary was determined with the help of various calibration methods. Diffusion coefficients of aqueous tetraalkylammonium perchlorates, Me₄NClO₄, and Et₄NClO₄, were measured at 25°C in the concentration range 10^–3 to 5×10^–2 mol-dm^–3, and the slightly soluble Pr₄NClO₄ up to 1×10^–2 mol-dm^–3. The slope of linear plots ofD vs. is in agreement with theory, in contrast to the limiting valuesD ₀, which all deviate by about –5% from the Nernst-Hartley values.     

Activity and Osmotic Coefficients from the Emf of Liquid-Membrane Cells. VII: Co(ClO4)2, Ni(ClO4)2, K2SO4, CdSO4, CoSO4, and NiSO4

The activity coefficients of CdSO₄ CoSO₄, and NiSO₄ are determined from the emf of liquid-membrane cells, like those described in the papers I–VI of this series. The activity coefficients of the auxiliary salts Co(ClO₄)₂, Ni(ClO₄)₂, and K₂SO₄, needed to eliminate the problem of extrapolation to infinite dilution of the 2–2 salts, are also measured. CdSO₄ CoSO₄ and NiSO₄ in the dilute region deviate downward from the limiting law by a larger extent than believed in the past, thus creating the need for the activity coefficients to be recalculated and systematically lowered by 8–16%. The activity coefficients of Co(ClO₄)₂ and Ni(ClO₄)₂, too, need to be corrected by around –3%. For K₂SO₄, the original values, although scattered, were substantially correct. Pitzer's theory best-fit parameter, able to provide the activity and osmotic coefficients of the salts considered, are reported.     

Osmotic and activity coefficients of aqueous lithium sulfate solutions at 40°C

The osmotic coefficients for aqueous lithium sulfate solutions were experimentally determined at 40°C. Sodium chloride served as the isopiestic standard for the calculation of osmotic coefficients. The molality ranges covered in this study correspond to about 0.1–2.5 mol-kg^–1. The system of equations developed by Hamer-Wu and Pitzer were used to fit each set of osmotic coefficients. The parameters obtained from the fit were used to calculate the activity coefficients.     

Thermodynamics of calcium chloride in highly concentrated aqueous solution and in hydrated crystals

Measured values of the pressure of H₂O over saturated solutions in equilibrium with the dihydrate, tetrahydrate or hexahydrate of CaCl₂ are converted to osmotic coefficients and compared with literature values for solutions of smaller molality. It is found that the osmotic coefficient is constant, within the uncertainty, from about 7 mol-kg^–1 to soturation at all temperatures from 25 to 100°C. From this simple approximation, the activity coefficient is calculated for high molalities and at saturation. By combination of these results with other established data, entropies and Gibbs energies of formation are calculated for the crystalline hydrates of CaCl₂.