The Semi-ideal Solution Theory. 4. Applications to the Densities and Electrical Conductivities of Mixed Electrolyte and Nonelectrolyte Solutions

Densities and electrical conductivities were measured for the ternary systems NaCl–mannitol(C₆H₁₄O₆)–H₂O, KCl–glycine(NH₂CH₂COOH)–H₂O, KCl–mannitol–H₂O, and NaBr–mannitol–H₂O at 298.15 K. Densities of the binary systems KCl–H₂O, NaBr–H₂O, glycine–H₂O and conductivities of the binary system NaBr–H₂O at 298.15 K were also measured. The measured densities were used to check the predictions of the semi-ideal solution theory. A new approach for predicting the conductivity of ternary electrolyte−nonelectrolyte mixture solutions in terms of the properties of their binary solutions of equal water activity is presented and compared with the measured values. The results show that the semi-ideal solution theory can provide good predictions for the densities and conductivities of the tested ternary electrolyte−nonelectrolyte solutions from the properties of their binary subsystems.     

A New Predictive Equation for the Depression in Freezing Points of Multicomponent Aqueous Solutions Conforming to the Linear Isopiestic Relation

The linear isopiestic relation has been used together with a well-known thermodynamic equation to establish a new predictive equation for freezing point depression. This equation can provide predictions for multicomponent solutions conforming to the linear isopiestic relation using only information on the corresponding binary subsystems. The predictive capability of the equation has been tested by comparing with the experimental data at 25°C reported in the literature and particularly those of Pathwardhan and Kumar. The systems used are NaCl—MgCl₂—H₂O, NaCl—BaCl₂—H₂O, NaCl—CaCl₂—H₂O, LiCl—NaCl—H₂O, LiCl—KCl—H₂O, LiCl—CsCl—H₂O, NaCl—KCl—H₂O, and NaBr—KBr—H₂O. The predictions of the two equations agree well with the experimental data although our new equation is, in general, better.     

Conductivities of Several Ternary Electrolyte Solutions and Their Binary Subsystems at 293.15, 298.15, and 303.15 K

Conductivities were measured for the ternary systems NaNO₃–KNO₃–H₂O, NaCl–BaCl₂–H₂O, NaCl–LaCl₃–H₂O, and their binary subsystems NaNO₃–H₂O, KNO₃–H₂O, NaCl–H₂O, BaCl₂–H₂O, and LaCl₃–H₂O at (293.15, 298.15 and 303.15) K. The results were used to verify the generalized Young’s rule and the semi-ideal solution theory. Comparison of the results shows that the average relative differences between the predicted and measured conductivities are ≤4.2×10⁻³ for NaNO₃–KNO₃–H₂O, ≤4.6×10⁻³ for NaCl–BaCl₂–H₂O, and ≤8.9×10⁻³ for NaCl–LaCl₃–H₂O, indicating that the generalized Young’s rule and the semi-ideal solution theory can provide good predictions for the conductivity of mixed electrolyte solutions in terms of the data from their binary subsystems.     

A New Predictive Equation for the Surface Tensions of Aqueous Mixed Ionic Solutions Conforming to the Linear Isopiestic Relation

The linear isopiestic relation has been used, together with the fundamental Butler equations, to establish a new simple predictive equation for the surface tensions of the mixed ionic solutions. This newly proposed equation can provide the surface tensions of multicomponent solutions using only the data of the corresponding binary subsystems of equal water activity. No binary interaction parameters are required. The predictive capability of the equation has been tested by comparing with the experimental data of the surface tensions for the systems HCl–LiCl–H₂O, HCl–NaClO₄–H₂O, HCl–CaCl₂–H₂O, HCl–SrCl₂–H₂O, HCl–BaCl₂–H₂O, LiCl–NaCl–H₂O, LiCl–KCl–H₂O, NaCl–KCl–H₂O, KNO₃–NH₄NO₃–H₂O, and LiCl–NaCl–KCl–H₂O at 298.15 K; KNO₃–NH₄Cl–H₂O, KBr–Sr(NO₃)₂–H₂O, NaNO₃–Sr(NO₃)₂–H₂O, NaNO₃ –(NH₄)₂SO₄–H₂O, KNO₃–Sr(NO₃)₂– H₂O, NH₄Cl–Sr(NO₃)₂–H₂O, NH₄Cl– (NH₄)₂SO₄–H₂O, KBr–KCl–H₂O, KBr–KCl–NH₄Cl–H₂O, KBr–KNO₃– Sr(NO₃)₂–H₂O, KBr–NH₄Cl–Sr(NO₃)₂–H₂O, KNO₃–NH₄Cl–Sr(NO₃)₂–H₂O, and NH₄Cl–(NH₄)₂SO₄–NaNO₃–H₂O at 291.15 K; and KBr–NaBr–H₂O at temperatures from 283.15 to 308.15 K. The agreement is generally quite good.     

Diagramme Polythermique Du Systeme Ternaire KCl–FeCl2–H2O Entre 0 Et 70°C

Polytherm diagram of the ternary system KCl–FeCl₂ –H₂ O between 0 and 70°C. Phase equilibria in the KCl–FeCl₂ –H₂ O system were studied over the temperature range 0–70°C by conductimetric and analytical methods. A solubility polytherm of the system was constructed. We have observed the crystallization fields of the KCl and FeCl₂ 6H₂ O (at 0°C), KCl and FeCl₂ 4H₂ O (at 15, 30 and 40°C) and KCl, FeCl₂ 4H₂ O and of a double salt KClFeCl₂ 2H₂ O are obtained at 70°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermodynamics of aqueous mixtures of sodium chloride,potassium chloride,sodium sulfate,and potassium sulfate at 25°C

Aqueous solutions of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate can be mixed in six ways to give ternary mixtures. Two of these have already been studied and results are now presented for the remaining four systems: H₂O–NaCl–K₂SO₄, H₂O–Na₂SO₄–K₂SO₄, H₂O–KCl–Na₂SO₄, and H₂O–KCl–K₂SO₄.     

Activity coefficients for NaBr in aqueous ternary solutions with sodium propionate and butyrate from EMF measurements

The activity coefficients of NaBr in the NaBr–NaPropionate–H₂O and NaBr–NaButyrate–H₂O systems were determined from EMF measurements at constant total ionic strength of 0.1 0.5 1.0 1.5 2.0 and 2.5 mol-kg^–1 and at 25° C. The activity coefficients were fitted using Scatchard, Pitzer and Lim equations. Finally the excess Gibbs free energy of these mixtures were also calculated.     

Thermochemistry of Bu<Subscript>4</Subscript>NBr solutions in binary solvents containing formamide

The heats of solution of tetrabutylammonium bromide have been measured in mixtures of formamide (FA) with methanol (MeOH) and ethylene glycol (EG) at 313.15 K by calorimetric method. The standard enthalpies of solution in binary mixtures have been extrapolated to infinite dilution by Redlich–Rosenfeld–Meyer type equation using the literary data at 298.15 K and the present paper data at 313.15 K. The Debye–Hückel limiting law slope A _H required for calculation of the ∆_sol H ⁰ value has been obtained with application the new additive scheme of determination of the physic-chemical characteristics of binaries. The scheme is tested on the example of Bu₄NBr solutions in FA–MeOH mixture at 298.15 K. Its application yields the ∆_sol H ⁰ value very closed on the ones determined with the real (non-additive) characteristics of binaries. The standard enthalpies of solution extrapolated by Redlich–Rosenfeld–Meyer type equation are in a good agreement with the ones computed in terms of the Debye–Hückel theory in the second approximation. The heat capacities characteristics of Bu₄NBr have been calculated in H₂O–FA, MeOH–FA and EG–FA mixtures using the literary and present data. The sequence of solvents H₂O > FA > EG > MeOH located on their ability to solvophobic solvation found by us earlier for enthalpic characteristics is confirmed by the ∆C _p ⁰ values. The comparison of thermochemical characteristics of Bu₄NBr solutions in aqueous and non-aqueous mixtures containing FA has been carried out. The own structure of water remains in the region of small additions of formamide to co-solvents. It considerably differs the H₂O–FA mixture from the investigated non-aqueous systems.     

Non-ideal properties of the TRIS—TRIS·HCl−NaCl−H2O buffer system in the 0–40 °C temperature interval. Application of the pitzer equations

The buffer solution TRIS—TRIS·HCl−NaCl−H₂O was studied in the 0–40 °C temperature region and ionic strength interval of (0.1–4)m (m is molality) by the e.m.f. method using two types of cells without liquid junction composed of platinum-hydrogen, silverchloride, and sodium-glass electrodes. For temperatures of 5 and 15 °C and the (1–4)m concentration region, the osmotic coefficients of the TRIS·HCl−H₂O solutions were measured by the isopiestic method. The results were processed in the framework of the Pitzer method, and the parameters of interaction of the components of the buffer system were calculated. The associative character of the interactions in the TRIS·HCl−H₂O solution was shown. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 670–675, April, 2000.     

Tracer (self)-diffusion of potassium ion in NaCl−KCl−H2O mixtures at 25°C

Tracer (self)-diffusion coefficients of K⁺ have been measured using the diaphragm cell in seven compositions of the NaCl–KCl–H₂O system. These data complete the full set of isothermal vector transport properties for five of these compositions.     

Thermodynamic representation of the NaCl + Na2SO4 + H2O system with electrolyte NRTL model

A comprehensive thermodynamic model based on the electrolyte NRTL (eNRTL) activity coefficient equation is developed for the NaCl + H₂O binary, the Na₂SO₄ + H₂O binary and the NaCl + Na₂SO₄ + H₂O ternary. The NRTL binary parameters for pairs H₂O-(Na⁺, Cl⁻) and H₂O-(Na⁺, SO₄²⁻), and the aqueous phase infinite dilution heat capacity parameters for ions Cl⁻ and SO₄²⁻ are regressed from fitting experimental data on mean ionic activity coefficient, heat capacity, liquid enthalpy and dissolution enthalpy for the NaCl + H₂O binary and the Na₂SO₄ + H₂O binary with electrolyte concentrations up to saturation and temperature up to 473.15 K. The Gibbs energy of formation, enthalpy of formation and heat capacity parameters for solids NaCl_(s), NaCl·2H₂O_(s), Na₂SO_4(s) and Na₂SO₄·10H₂O_(s) are obtained by fitting experimental data on solubilities of NaCl and Na₂SO₄ in water. The NRTL binary parameters for the (Na⁺, Cl⁻)-(Na⁺, SO₄²⁻) pair are regressed from fitting experimental data on dissolution enthalpies and solubilities for the NaCl + Na₂SO₄ + H₂O ternary.     

Conductance Studies on Complex Formation Between Aza-18-Crown-6 with Ag+, Hg2+ and Pb2+ Cations in DMSO–H2O Binary Solutions

The complexation reactions between Ag⁺, Hg²⁺ and Pb²⁺ metal cations with aza-18-crown-6 (A18C6) were studied in dimethylsulfoxide (DMSO)–water (H₂O) binary mixtures at different temperatures using the conductometric method. The conductance data show that the stoichiometry of the complexes in most cases is 1:1(ML), but in some cases 1:2 (ML₂) complexes are formed in solutions. A non-linear behaviour was observed for the variation of log K _f of the complexes vs. the composition of the binary mixed solvents. Selectivity of A18C6 for Ag⁺, Hg²⁺ and Pb²⁺ cations is sensitive to the solvent composition and in some cases and in certain compositions of the mixed solvent systems, the selectivity order is changed. The values of thermodynamic parameters (ΔH _c^o, ΔS _c^o) for formation of A18C6–Ag⁺, A18C6–Hg²⁺ and A18C6–Pb²⁺ complexes in DMSO–H₂O binary systems were obtained from temperature dependence of stability constants and the results show that the thermodynamics of complexation reactions is affected by the nature and composition of the mixed solvents.     

Effect of oxygen activity and water partial pressure to degradation rate of Ni cermet electrode contacting Zr<Subscript>0.84</Subscript>Y<Subscript>0.16</Subscript>O<Subscript>1.92</Subscript> electrolyte

The time curves of full polarization resistance of Ni cermet electrode modified with CeO_{2 − δ} additive were studied by means of impedance spectroscopy in binary gas mixtures x% H₂ + (100 − x)% H₂O, 10% CO + 90% CO₂ and multicomponent gas mixtures H₂ + CO₂ + H₂O + CO + Ar of various composition at the temperature of 900°C. The Ni cermet electrode degradation rate in binary gas mixtures H₂ + H₂O was shown to increase sharply at the partial water pressure over 45%. The Ni cermet electrode degradation rate in the mixture of 10% CO + 90% CO₂ was significantly lower than that in 10% H₂ + 90% H₂O. The major changes in the electrode characteristics upon long exposure in working conditions were accounted for by changes in the high-frequency partial polarization resistance. In the course of long testing, the electrode microstructure was not significantly changed. In the presence of hydrogen-containing components (H₂ and H₂O), the carbon-containing components (CO and CO₂) were shown to make an insignificant contribution to the current generation processes in Ni cermet electrode. It was suggested that strong degradation of Ni cermet electrode was caused by poisoning its reaction sites with strongly linked adsorption forms of water (hydroxyls) at the positive charge of electrode.     

Isopiestic Measurement of the Osmotic Coefficients of Aqueous {xH 2 SO 4 + (1− x)Fe 2 (SO 4 ) 3 } Solutions at 298.15 and 323.15 K

This study measures the osmotic coefficients of {xH₂SO₄ + (1−x)Fe₂(SO₄)₃}(aq) solutions at 298.15 and 323.15 K that have ionic strengths as great as 19.3 mol,kg⁻¹, using the isopiestic method. Experiments utilized both aqueous NaCl and H₂SO₄ as reference solutions. Equilibrium values of the osmotic coefficient obtained using the two different reference solutions were in satisfactory internal agreement. The solutions follow generally the Zdanovskii empirical linear relationship and yield values of a _w for the Fe₂(SO₄)₃–H₂O binary system at 298.15 K that are in good agreement with recent work and are consistent with other M₂(SO₄)₃–H₂O binary systems.     

Entwässerung von Kristallhydraten als Verfahren zur Reinigung von Salzen, 6. Mitt.: Entwässerung von NaBr·2H2O mit organischen Lösungsmitteln sowie bei der Temperatur des Übergangs in seiner gesättigten Lösung

Zusammenfassung Es wurde die Gehaltsänderung an nicht-isomorpher Verunreinigung mit Na₂CrO₄ bzw. Na₂SO₄ bei der Entwässerung von NaBr·2H₂O in seiner gesätt. Lösung bei der Übergangstemperatur untersucht. Ferner wurde der Entwässerungs-prozeß dieses Kristallhydrats unter Wirkung von geeigneten Lösungsmitteln (C₂H₅OH, Aceton, Isopropylalkohol) sowie das Verhaten der Verunreigung an Na₂CrO₄ bei der Entwässerung von NaBr·2H₂O verfolgt. Es wurde festgestellt, daß der Verlauf der Löslichkeitskurve eines Salz-Kristallhydrats keinen Einfluß auf den beobachteten Reinigungseffekt der Kristallmasse bei der Überganstemperatur in der gesätt. Lösung ausübt, wenn eine strukturelle Änderung des Kristallgitters vorhanden ist. Zusammen mit den sonstigen Faktoren hat auch die Menge des bei dem Entwässerungsprozeß des NaBr·2H₂O abgeschiedenen Kristallwassers einen gewissen Einfluß auf den Reinigungseffekt.

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Dehydration of Crystal Hydrates as a Method of Purifying Salts, VI: Dehydration of NaBr·2H₂O with Organic Solvents, also at the Temperature of Its Transformation to a Saturated Solution

The alteration of the content of the non-isomorphous contaminants Na₂CrO₄ and Na₂SO₄ during the dehydration of NaBr·2H₂O in its saturated solution at the transition temperature has been investigated. Further, the dehydration process of this crystallo hydrate under the action of solvents (C₂H₅OH, acetone, isopropyl alcohol), as well as the behaviour of the Na₂CrO₄ contaminant during the dehydration of NaBr·2H₂O, were studied. It was established that the course of the solubility curve of a hydrated salt has no influence upon the observed purification effect of the crystalline mass at the transition temperature in the saturated solution, if there is structural alteration of the crystal lattice. Simultaneously with the other factors, the amount of crystal water, given off during the dehydration of NaBr·2H₂O, also has a certain influence upon the purification effect.

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Mit 3 Abbildungen     

Phase Behavior of Aqueous Na–K–Mg–Ca–Cl–NO<Subscript>3</Subscript> Mixtures: Isopiestic Measurements and Thermodynamic Modeling

A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl⁻ and NO₃⁻ ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 °C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 °C. The measurements have been performed using Oak Ridge National Laboratory’s (ORNL) previously designed gravimetric isopiestic apparatus, which can also detect solid phase precipitation. In addition to various Na–K–Mg–Ca–Cl–NO₃ systems, results are reported for LiCl solutions. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid–liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor–liquid and solid–liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems.     

Ruthenium complexes of 3-hydroxy-4-pyranones and of 3-hydroxy-4-pyridinones

Reactions of hydrated ruthenium chloride with 2-methyl-3-hydroxy-4-pyranone, ethylmaltol (etmaltH) and with 1,2-dimethyl-3-hydroxy-4-pyridinone (dmppH) are described. The former results in the formation of Ru(etmalt)₃, but the course of the latter depends on conditions, producing the earlier-characterised Ru(dmmp)₃Cl in ethanol–water solution, Ru(dmmp)₃ in aqueous solution under mild conditions, and Ru(dmpp)₂(H₂O)₂ after extended refluxing. EXAFS studies established ruthenium-oxygen distances in Ru(etmalt)₃ and in Ru(dmmp)₃ · 6H₂O. Solubilities of Ru(dmmp)₃ in methanol–water mixtures reveal greater solubility in methanol than in water, and indications of a modest solubility maximum, and thus synergic solvation, in methanol-rich mixtures.     

Solubilities and Transfer Chemical Potentials for Cobalt(III) Complexes in <Emphasis Type="BoldItalic">t</Emphasis>-butanol– <Emphasis Type="BoldItalic">i</Emphasis>-propanol–, and ethanol–water Mixtures

Solubilities in t-BuOH–, i-PrOH–, and EtOH–H₂O mixtures at 298.2 K are reported for a number of salts of mono- and bi-nuclear cobalt(III) complexes. From these solubilities and published single ion transfer chemical potentials, on the TATB (Ph₄As ⁺≡ BPh₄^-) assumption, transfer chemical potentials have been derived for most of these cobalt(III) complexes. The results and trends are discussed in relation to those for other ions and complexes. Effects of ligand nature for transfer to t-BuOH–H₂O mixtures are detailed and, for a selection of complexes, trends for transfer of a given complex to t-BuOH–, i-PrOH–, EtOH– , and MeOH– H₂O mixtures are compared.     

Slow proton exchange in water in the gas phase

To study proton exchange in water the technique of quantitative measurements of water content at very low concentrations of water in solutions or at low vapor pressure in the gas phase (for water content of 1–10 μg/ml) has been developed. Under these conditions the rate of proton exchange slows down significantly. In particular, in mixtures of H₂O and D₂O vapors under the pressure of a 10–17 mm Hg proton life-time during the exchange process reaches the values of 10–30 min. The lifetime was measured using the gradual slow growth of the signal intensity of the mixed isotopomer HDO.     

The mutual diffusion coefficients of NaCl−H2O and CaCl2−H2O at 25°C from Rayleigh interferometry

The volume-fixed mutual diffusion coefficients of NaCl–H₂O and CaCl₂–H₂O have been measured to an accuracy of 0.1–0.2%, from dilute solutions to high concentrations, by free diffusion Rayleigh interferometry. These diffusion coefficients are compared to other diffusion data for these salts, obtained from Guoy interferometry and the conductometric method. Discrepancies between data in the literature are resolved using the present results. Some diffusion coefficients have also been measured for KCl–H₂O and NH₄Cl–H₂O.Work performed in part under the auspices of the U.S. Department of Energy by the Lawrence Livermore Laboratory under contract number W-7405-ENG-48.Reference to a company or product name does not imply approval or recommendation of the product by the University of California or the U.S. Department of Energy to the exclusion of others that may be suitable.This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Department of Energy, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.University of Illinois at Urbana-Champaign; tenure served as a participating guest at Lawrence Livermore Laboratory.