Calculation of the transport properties of aqueous species at pressures to 5 KB and temperatures to 1000°C

The limiting equivalent conductances at temperatures from 0° to 1000°C and pressures from 1 to 5000 bars of a large number of aqueous ions have been calculated from limiting equivalent conductances of electrolytes reported in the literature. The limiting equivalent conductances of individual ions typically increase by a factor of about 15 with increasing temperatures from 0° to 1000°C and decrease about 30 percent with increasing pressure from 1 to 5 kb. The equivalent conductance of H₂O approximated by the sum of the limiting equivalent conductances of H⁺ and OH^– is essentially independent of pressure, but increases from about 350 to a maximum of approximately 1800 S-cm²-equiv^–1 in response to an increase in temperature from 0° to 500°C at 1kb. Stokes' law radii and Walden products generated from the computed limiting equivalent conductances of ions exhibit changes over the temperature and pressure range of interest by as much as 100 percent for all of the ions except H⁺ and OH^–, which vary by an order of magnitude. Apparent solvation numbers calculated as a function of pressure and temperature from the Stokes' law radii using the volume and dielectric constant of H₂O and Born coefficients of the individual ions approach infinity at the critical point of H₂O. Residual friction coefficients as a general rule approach zero as temperatures increases to 1000°C. The excess limiting equivalent conductances of the hydrogen and hydroxyl ions computed from the differences between the limiting equivalent conductances of HCl and KCl, and NaOH and NaCl, respectively, increases with increasing pressure, and maximize at 250°C.     

Ion association of lithium bromide,chloride and picrate and of sodium picrate in 2-propanol at 25°C. I. Conductance measurements

The molar conductances of lithium bromide, chloride and picrate, and of sodium picrate have been determined as a function of salt concentration in 2-propanol solvent at 25°C. Values of the limiting molar conductance, Λ₀, and ion pair formation constant K_A have been calculated for each of these salts using both the Fuoss 1978 and the Lee and Wheaton conductance equations. Both of these equations yield comparable results for the present systems. The limiting conductances found here are compored with those reported for lithium chloride in 1-propanol and acetone and with those for the picrates in acetone and 2-butanone, all solvents of comparable dielectric constants. The Rasaiah-Friedman square mound potential, h_+?/kT, has been calculated for each salt using the approach of Justice and Justice. These values for 2-propanol have been compared with those for lithium chloride in 1-propanol and in acetone and for the picrates in acetone and 2-butanone.     

Conductance of substituted amine perchlorates and picrates in N-methyl-2-pyrrolidinone at 25°C

Conductance measurements of 16 perchlorates and picrates of substituted ammonium cations have been made in N-methyl-2-pyrrolidinone (NM-2-Py) at 25°C. To aid in the estimation of ionic conductances, measurements of tetrabutyl-ammonium tetraphenylborate were also included. The data were analyzed by both the full Pitts equation and the expanded Pitts equation in order to obtain limiting molar conductances _o and the ion association constants K _A . The results showed that pyridinium perchlorate and piperidinium, 2,4-dimethyl-pyridinium, 2,4,6-trimethylpyridinium picrates and tetrabutylammonium tetraphenylborate appear to be completely dissociated in NM-2-Py. The values of K _A for the other salts range from 1 to 36 dm³-mol^–1. Limiting molar conductances for the cation were based on the Coplan-Fuoss assumption.On leave 1973–1975 from University of Gdask, Poland.     

Ion Association and Solvation Behavior of Some 1-1 Electrolytes in 2-Ethoxyethanol Probed by a Conductometric Study

Precise measurements of the electrical conductances of solutions of potassium thiocyanate (KCNS), ammonium thiocyanate (NH₄CNS), sodium nitrate (NaNO₃) and ammonium nitrate (NH₄NO₃) in 2-ethoxyethanol (EE) at temperatures 35, 40, 45 and 50,^∘C are reported. The conductance data have been analyzed by the 1978 Fuoss conductance equation. A thermodynamic analysis of the ionic association processes has also been made and the Coulombic forces are found to play a major role in the association processes. The ionic contributions to the limiting equivalent conductances have been determined using the reference electrolyte method. Strong association was found for all these electrolytes in this solvent medium. The cations are found to be substantially solvated in 2-ethoxyethanol, whereas the anions appear to have only weak interaction with the solvent molecules.     

The Representation of Electrical Conductances for Polyvalent Electrolytes by the Quint–Viallard Conductivity Equation

Electrical conductivities of dilute aqueous solutions of aluminum sulfate were determined and analyzed in terms of a strongly associated electrolyte of the 3:2 type. The conductivities reported here were determined from 15 to 35 °C. Representation of conductances, in the framework of the ion association model, was performed using the Quint–Viallard conductivity equations for highly charged electrolytes and the Debye–Hückel expression for activity coefficients. Determined apparent association constants K _a(T) were considered as adjustable parameters. The determined limiting conductances of the trivalent aluminum ion λ⁰((1/3)Al³⁺) are considerably higher than those reported in the literature. Available specific conductivities in concentrated aqueous solutions of aluminum sulfate were fitted by a new empirical equation with only three adjustable parameters.     

Ionic Association and Mobility IV. Ionophores in Dimethylsulfoxide at 25°C

The results of conductance measurements on pyridinium picrate, tetraphenylo-sonium picrate, potassium picrate, tetraphenylantimony picrate, tetrapropylam-monium, tetrafluoroborate, tetramethylammonium hexafluorophosphate ion association noncoulombic interaction in dimethyl sulfoxide (DMSO) at 25°C in the concentration range 1–15×10^–4 M are reported. The data were analyzed by the Justice modification of the Fuoss–Hsia equation. Except for pyridinium picrate all salts studied were found to be associated.Application of the Justice Barthel–Bjerrum model of ion association permitted calculation of the noncoulombic portion of the potential of mean force, W _±. Ionic limiting conductances were calculated for six ions using known values of previously determined transport numbers. A table of most current limiting ionic conductances for a variety of ions in DMSO at 25°C has been established.     

Conductance study of association in aqueous CaCl2, Ca(CH3COO)2, and Ca(CH3COO)2.nCH3COOH from 348 to 523 K at 10 MPa

The conductances of aqueous CaCl2, Ca(CH3COO)2, and Ca(CH3COO)2.nCH3COOH were measured from 348 to 523 K at pressures near 10 MPa using a flow conductometric technique. The first association constant for calcium chloride and the first and second association constants for calcium acetate in water, were derived from a least-squares fit of the measurements to a conductance model in which activity coefficients were calculated using the mean spherical approximation (MSA) and the conductance was modeled by the Turq, Blum, Bernard, and Kunz (TBBK) equation, plus a mixture model.     

Representation of Electrical Conductances for Polyvalent Electrolytes by the Quint-Viallard Conductivity Equation. Universal Curves of Limiting Conductances and Walden Products of Electrolytes in Mixed Solvents. Part 5. Symmetrical 2:2, 3:3 and Unsymmetrical 1:2, 2:1 and 1:3 Type Electrolytes

Conductivities of symmetrical and unsymmetrical electrolytes of 2:2, 3:3, 1:2, 2:1 and 1:3 types in ethanol–water and the 1,4-dioxane–water mixtures were analyzed using the Quint-Viallard conductivity equation and taking into account the ion association effect. The molar limiting conductances and the ion association constants were reexamined for various multivalent electrolytes. One non-aqueous system, methanol–ethylene glycol mixtures, was also considered. The limiting conductances were also examined in the framework of universal curves of limiting conductances and the excess Walden products introduced by the author. These new concepts in the analysis of conductance data allow the estimation of values of limiting conductances of electrolytes or ions, to give an indication about the quality of the conductivity measurements and the type of interactions expected in the systems. It was found that for any type of electrolyte only one universal curve of limiting conductances exists. In the water-rich mixtures, attractive interactions (structure-making effects) are expected when electrolytes are added to mixtures with ethanol or with 1,4-dioxane. In contrast, in ethylene glycol–methanol-rich mixtures repulsive interactions (structure-breaking effects) are more likely.     

Volumetric properties and electrolytic conductances of aqueous ternary mixtures of hydrogen chloride and some transition metal chlorides at 25°C

Densities and electrolytic conductances of hydrochloric acid and ternary aqueous solutions of HCl with manganese(II), copper(II), and cadmium(II) chlorides, respectively, have been measured from about 0.2 m to ternary saturation points at several constant molalities of the salt, MnCl₂, or that of HCl for the system MnCl₂–HCl–H₂O as well as at constant total molal ionic strength of I=10.0 for all the three ternary systems (Mn, Cu, Cd)Cl₂–HCl–H₂O at 25°C. The molality dependence of the calculated volume of mixing changes V _m and of the specific conductances are discussed on the basis of the different degrees of complex formation of the bivalent transition metal chlorides in the presence of excess amounts of chloride anions in the form of HCl. It was to be seen from the present results that even the manganese(II) chloride, which behaves as a fairly strong electrolyte in dilute aqueous solutions, is considerably complexed at high concentrations of HCl, with the degree of complexation of the cations increasing in the sequence Mn^2–2–2–.Part of this publication was presented at the XIX International Conference on Solution Chemistry (XIX ICSC), Lund, Sweden, August 15–18, 1988.     

Transference numbers for anhydrous methanol solutions at 10 and 25°C

Transference numbers are reported for LiCl and NaCl in methanol at 25°C and for NaCl, KCl, and Bu₄NBr in methanol at 10°C. The potentiometric moving-boundary method as developed by Kay and Fratiello was employed to give a precision of about 0.05% and an accuracy of at least 0.1% as indicated by two independent determinations of the conductances of the Cl^– and Br^– ions. The data are extrapolated by the Fuoss-Onsager theory, and the magnitude of the electrophoretic effect is calculated as described by Kay and Dye. The agreement with this theory is quite good at both temperatures, although the å value required in the case of Bu₄NBr is considerably larger than that obtained from conductance data. This agreement contrasts with that obtained for ethanol and acetone solutions where the measured electrophoretic effect is considerably larger than the corresponding calculated values. The importance of this fact in the determination of ion-pair association constants is discussed.     

Conductivities of 1∶1 salts in 2-cyanopyridine

Electrolytic conductivities of eight simple 11 electrolytes have been measured in dilute solutions of 2-cyanopyridine (2CNP) at 30°. Infinite dilution mobilities and association constants were calculated using the Fuoss-Hsia equation. With the exception of LiCF₃SO₃ all salts show very little association, consistent with the very high dielectric constant of 2CNP. The weak association which does occur is attributed to weak ion-solvent interactions. No evidence was found for triple ion formation. Conductivities of concentrated solutions of LiAsF₆ in 2CNP increase slowly with concentration reaching a maximum at a concentration of around 0.65 mol-dm^–3. These conductances are slightly lower than those in propylene carbonate which has a lower dielectric constant and a higher viscosity. Conductivities of concentrated LiAsF₆ solutions in 2CNP mixtures with acetonitrile vary monotonically, consistent with solution viscosities, and show no sign of the maximum commonly observed in mixed organic solvents.     

Mixed ternary ion associate formation between xanthene dye, cinchona-alkaloid and quaternary ammonium ion and its application to the determination of trace amounts of quaternary ammonium salts in pharmaceuticals

Xanthene dyes such as eosin and tetraiodofluorescein form 1:2 ion associates with quaternary ammonium ions at pH 7-9; however, the development of color in the organic solvent is poor. When a quaternary ammonium salt is added in the extractable 1:2 associate formed between a xanthene dye and a cinchona-alkaloid in the neutral media, a mixed ternary ion associate (xanthene dye:cinchona-alkaloid:quaternary ammonium ion=1:1:1) is formed. Its extractability is enhanced due to the more bulky associate formation. The ion association caused by addition of cinchona-alkaloids is unique. Of the cinchona-alkaloids, quinidine and cinchonidine with tetraiodofluorescein show excellent effects on sensitivity and extractability. Eosin and tetraiodofluorescein are useful as ion association reagents in the ion associate formation. The apparent molar absorptivities are about 1×10⁵ l mol⁻¹ cm⁻¹ and the calibration range for quaternary ammonium salt is from 2.5×10⁻⁷ to 1.5×10⁻⁶ M. The proposed method is applicable to the selective and sensitive determination of cetylpyridinium chloride, berberine chloride and benzethonium chloride in pharmaceuticals.     

The conductance of divalent Ions in H2O at 10 and 25°C and in D2O

Precise conductance measurements are reported for potassiumm-benzenedisulfonate and ferricyanide, for calcium, strontium, barium, and manganese chloride, and for manganese and potassium sulfate in D₂O at 25°C. Measurements were also carried out in water at 10 and 25°C for all the salts with the exception of K₃Fe(CN)₆ at 10°C. Two runs are reported for sodium sulfate in water at 25°C. Limiting conductances of these ions are discussed in terms of solvent structural effects. The association constant for MnSO₄ is found to be the same in H₂O and D₂O.     

Electrical Conductances of Tetrabutylammonium and Decamethylferrocenium Hexafluorophosphate in Organic Solvents

The electrical conductances of tetrabutylammonium hexafluorophosphate in acetone and of decamethylferrocenium hexafluorophosphate in acetone, acetonitrile 1,2-dichloroethane, and dichloromethane have been measured at 25^°C. The Walden product of the Bu₄N⁺ cation and the PF₆^- anion in acetone and other solvents is discussed in relation to the dielectric friction. The electric conductance at infinite dilution and the association constant of decamethylferrocenium hexafluorophosphate were determined in the four solvents investigated. The association constant of this electrolyte increases with decreasing reduced temperature, as expected in the framework of the association theory, within the primitive model of electrolytes.     

Electrical Conductance of Some Symmetrical Tetraalkylammonium and Alkali Salts in N,N-Dimethylacetamide at 25°C

Precise measurements of electrical conductances of solutions of tetraethylammonium bromide, tetrapropylammonium bromide, tetrapentylammonium bromide, tetrahexylammonium bromide, tetraheptylammonium bromide, tetraocytylammonium bromide, sodium tetraphenylborate, and potassium tetraphenylborate in N,N-dimethylacetamide at 25^°C are reported for the concentration range 0.005-0.015 mol-dm^–3. The conductance data have been analyzed by the 1978 Fuoss conductance-concentration equation in terms of the limiting molar conductance, the association constant, and the association diameter. The limiting ionic conductances have been estimated from the appropriate division of the limiting molar conductivity value of the reference electrolyte Bu₄NBPh₄. Slight ionic association was found for all these salts in this solvent medium. Tetraalkylammonium ions are found to be unsolvated in N,N-dimethylacetamide, whereas significant solvation has been noticed for sodium and potassium ions.     

Electrical conductances of tetrabutylammonium bromide and tetrapentylammonium bromide in 2-ethoxyethanol + water mixtures at 308.15, 313.15, 318.15 and 323.15 K

The electrical conductances of the solutions of tetrabutylammonium bromide (Bu₄NBr), and tetrapentylammonium bromide (Pen₄NBr) in 2-ethoxyethanol (1) + water (2) mixed solvent media containing 0.25, 50 and 0.75 mass fractions of 2-ethoxyethanol (w ₁) have been reported at 308.15, 313.15, 318.15 and 323.15 K. The conductance data have been analyzed by the 1978 Fuoss conductance–concentration equation in terms of the limiting molar conductance (Λ⁰), the association constant (K _A) and the association diameter (R). These two electrolytes are found to exist essentially as free ions in the solvent mixtures with w ₁ = 0.25 and 0.50 over the entire temperature range; however, slight ionic association was observed in the mixed solvent medium richest in 2-ethoxyethanol. The electrostatic ion–solvent interaction is found to be very weak for the tetraalkylammonium ions in the aqueous 2-ethoxyethanol mixtures investigated.     

Ion mobilities in DMF-water mixtures at 25°C

Densities and viscosities of mixtures of N,N-dimethylformamide (DMF) with water at 25°C have been determined. Limiting equivalent conductances of cesium chloride, potassium chloride, potassium bromide and potassium thiocyanate in these solvent mixtures at 25°C are presented together with corresponding values of ion association constants and distance of closest approach parameters. The transference number of the potassium ion has been determined in solvent mixtures ranging from 0 to 0.75 mol fraction in DMF in water at 25°C. The conductimetric Hittorf method has been used for both potassium bromide and potassium chloride in solutions of up to 0.496 mole fraction of DMF. For solutions of potassium thiocyanate in 0.5 and 0.75 mole fraction in DMF the cationic transference number has been determined using the moving boundary method. Stokes radii have been evaluated. Transport properties are examined in relation to-solvent properties such as composition, dielectric constant, excess volume of mixing and free volume.To whom correspondence should be addressed.     

Ionic association and mobility. III. Ionophores in propylene carbonate at 25°C

Conductance data are reported for (CH₃)₄NPF₆, (C₂H₅)₄NPF6, PyrHPic, (CH₃)₄NBF₄, and (C₇H₁₅)₄NPic in propylene carbonate at 25°C in the concentration range (4–16)×10^?4 M. The data for salts other than (C₂H₅)₄NPF₆ were analyzed by the Justice modification of the Fuoss-Hsia equation and these salts were found to be associated and to form solvent separated ion pairs. The data for (C₂H₅)₄NPF₆ which was found to be nonassociated were analyzed by use of the Fuoss-Onsager equation. Application of the Justice-Barthel procedure permitted calculation of the nonCoulombic contribution to the association process. Ionic limiting conductances of several ions were calculated by using known ionic limiting conductances of R₄N⁺ and Pic^? ions and molar conductances reported here.     

Representation of Electrical Conductances for Polyvalent Electrolytes by the Quint-Viallard Conductivity Equation. Part 4. Symmetrical 2:2, 3:3 and Unsymmetrical 2:1, 3:1 and 1:3 Type Electrolytes in Pure Organic Solvents

Conductivities of symmetrical and unsymmetrical electrolytes of 2:2, 3:3, 2:1, 3:1 and 1:3 charge types in pure organic solvents (methanol, ethanol, 1-propanol, dimethyl sulfoxide, acetonitrile, formamide, N-methylformamide, N,N-dimethylformamide, N-methylacetamide and N,N-dimethylacetamide) were analyzed using the Quint-Viallard conductivity equation and taking into account the ion association effect. The molar limiting conductances and the ion association constants were determined for various multivalent electrolytes in these solvents using the literature conductivities. In many cases, for the first time, it was possible to obtain consistent values of the limiting ionic conductances in organic solvents.     

Conductance of Some 1:1 Electrolytes in N,N-Dimethylacetamide at 25°C

Precise conductance measurements of solutions of lithium chloride, lithium bromide, lithium iodide, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, tetrabutylammonium bromide, and tetrabutylammonium tetraphenylborate in N,N-dimethylacetamide are reported at 25°C in the concentration range 0.005–0.015 mol-dm^–3. The conductance data have been analyzed by the 1978 Fuoss conductance equation in terms of the limiting molar conductance (⁰), the association constant (K _a), and the association diameter (R). The limiting ionic conductances have been estimated from an appropriate division of the limiting molar conductivity of the reference electrolyte Bu₄NBPh₄. Slight ionic association was found for all these salts in this solvent medium. The results further indicate significant solvation of Li⁺ion, while the other ions are found to be unsolvated in N,N-dimethylacetamide.