Volumetric properties of aqueous electrolytes at high temperature. III. B(OH)3−NaBx(OH)3x+1−NaOH mixtures up to 523 K

The densities of aqueous solutions resulting from the partial neutralization of boric acid with sodium hydroxide were measured as a function of concentration, between 375 K and 523 K at pressures close to saturation. The speciation in this system is complex, di- and triborate ions are present in addition to the monoborate ion. The concentration dependence of the apparent partial molar volume of the mixture can be described using the Pitzer equation only if the formation of the polyborate species in the concentrated solutions is taken into account. The partial molar volumes at infinite dilution for the diborate and triborate anions, obtained by assuming ideal mixing, are reported in the range of temperature studied.     

Molecular Interactions in Propylene Carbonate + <Emphasis Type="Italic">n</Emphasis>-Alkanols at 25 <Superscript>∘</Superscript>C

Densities and viscosities of the binary mixtures of propylene carbonate with methanol, ethanol, propanol, butanol, and hexanol, along with those of the pure liquids, were measured over the entire mole fraction range at 25 C. Using the experimental values of densities and viscosities , the excess molar volumes V^E, viscosity deviations , excess Gibbs energies of activation of viscous flow G^E, and Grunberg–Nissan interaction parameters d₁₂ were calculated from the linear dependence of these parameters on the composition of the mixtures.     

Aqueous solutions of azoniaspiroalkane halides. VI. Apparent molal volumes and apparent molal heat capacities of chlorides and iodides

Densities and heat capacities of aqueous solutions of azoniaspiroalkane halides, (CH₂) _n N⁺ (CH₂) _n X^– (where X=Cl, I andn=5,6), have been measured at 25°C using a flow densimeter and a flow microcalorimeter. The limiting apparent molal volumes (ø _v ) and apparent molal heat capacities (ø _cp ) obtained from these data are compared with those of the azoniaspiroalkane bromides and the corresponding tetraalkylammonium halides. The concentration dependence of ø _v and ø_cp are examined for clues on the influence of solute hydration, structure, and conformational flexibility on the excess functions of quaternary ammonium halides.     

Mixtures of 1-1 electrolytes: Densities and excess volumes of aqueous NaCl-NaBr solutions at 25°C

The relative densities and excess volumes of mixing are reported for the system consisting of aqueous NaCl and NaBr at 25°C at constant ionic strengths of 0.5, 1, 2, 3, and 4 mol kg^–1 of water. The measurements of densities are precise to 3 · 10^–6 g cm^–3. The densities, apparent molal volumes and excess volumes are analysed with the virial coefficients approach with excellent accuracy. The excess volumes are positive throughout.

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Mischung von 1 : 1-Elektrolyten: Dichten und Excess-Volumina von wäßrigen NaCl-NaBr-Lösungen bei 25°C

Zusammenfassung Die relativen Dichten und Excess-Volumina der Mischung werden für das System wäßriges NaCl-NaBr bei 25°C und einer konstanten Ionenstärke von 0.5, 1, 2, 3 und 4 mol kg^–1 Wasser berichtet. Die Dichtemessungen haben eine Genauigkeit von 3 · 10^–6 g cm^–3. Die Dichten, die effektiven molalen Volumina und die Excess-Volumina werden von der Virialkoeffizienten-Methode ausgezeichnet wiedergegeben. Die Excess-Volumina sind durchwegs positiv.

     

Excess volumes of binary mixtures of ethylbenzene with octanol,nonanol and dodecanol from 50 to 100°C and 0.1 to 7.5 MPa

The excess volume V ^E of binary mixtures of octanol, nonanol and dodecanol in ethylbenzene have been calculated from the densities measured with a vibrating tube densimeter at temperatures from 50 to 100 °C and at pressures from 0.1 to 7.5 MPa. The values of V ^E are positive for all the three mixtures in the complete temperature, pressure and mole fraction ranges studied. The maxima in V ^E is observed at 0.4 mole fraction of alkanol. The results are discussed in terms of specific interactions present in the binary mixtures. The second order thermodynamic quantities (V ^E /T)_p,(V ^E /P)_T and (V _E /P)_T which have been derived from the effect of temperature and pressure on V ^E , indicate an overall net creation of order in the binary mixtures of ethylbenzene with higher homologues of alkanols.     

Densities and apparent molal volumes of aqueous concentrated calcium chloride solutions from 50 to 200°C at 20.27 bar

Densities of aqueous calcium chloride solutions are reported for molalities up to 6.4 mol-kg^–1 at temperatures from 50 to 200°C and at 20.27 bar. Apparent molar volumes calculated from experimental densities were fitted to the equations of Rogers and Pitzer, and the temperature dependence of the Pitzer parameters were obtained. The standard deviation of fit for the apparent molar volumes is 0.21 cm³-mol^–1 from 50 to 200°C at 20.27 bar.     

Volumetric,Viscometric, and Refractive Index Behaviour of Glycine in Aqueous Diols at Different Temperatures

Densities, ρ, viscosities, η, and refractive indices, n_D, of glycine (Gly) (0.1 — 0.5 M) in aqueous 1,2‐ethanediol (1,2‐EtD), 1,2‐propanediol (1,2‐PrD), and 1,3‐butanediol (1,3‐BuD) (30% v/v) were measured at 298, 303, 308, and 313 K. Experimental values of ρ and η were used to calculate partial molar volumes, ?⁰_v, partial molar volumes of transfer of Gly from water to aqueous diol solutions, ?⁰_v(tr), Falkenhagen and Jones ‐Dole coefficients, A and B, respectively, free energies of activation of viscous flow, Δμ⁰*₁ and Δμ⁰*₂, per mole of solvent and solute, respectively, enthalpies, ΔH* and entropies, ΔS* of activation of viscous flow. Large positive values of ?⁰_v, and an increasing value of S_v*, for all the three mixtures at each temperature suggest the presence of strong solute‐solvent interaction, and this interaction decreases as the size of alkyl moiety increases from 1,2‐EtD to 1,3‐BuD. Positive ?⁰_v(tr) values tend to decrease with increasing the number of CH₂ group, thereby indicating that the electrostriction effect in diols follows the sequence; 1,2‐EtD > 1,2‐PrD > 1,3‐BuD. Small A values, with large values of B, are indicative of weak solute‐solute and strong solute‐solvent interactions that operate in the present systems, and that the magnitudes of B are in the sequence: 1,2‐EtD > 1,2‐PrD > 1,3‐BuD and, thus, the sequence represents the strength of interaction between Gly and diol molecules. Moreover, positive SB/ST values suggest the structure‐breaking nature of Gly in diol + water mixtures. The observed values of Δμ⁰*₂ fall in the sequence: 1,2‐EtD > 1,2‐PrD > 1,3‐BuD which, like ?⁰_v and S_v*, reinforce that Gly‐diol interaction decreases with subsequent addition of CH₂ group in diols. The trends in the variation of ΔH* and ΔS* with Gly concentration also reveal the presence of significant solute‐solvent interaction in all three systems. An almost linear increase in RD with an increasing amount of Gly reveals that Gly tends to increase the polarizability of the aqueous‐diol molecules under study. The variation of all these parameters with concentration of Gly and with temperature suggests the presence of strong solute‐solvent interaction, which decreases as the size of alkyl moiety in diols increases from 1,2‐EtD to 1,3‐BuD.     

Molar and partial molar excess volumes of di-n-butylamine with chloroalkanes at 25°C

Molar excess volumes and partial molar excess volumes are reported for binary mixtures of dibutylamine+dichloromethane, trichloromethane and tetrachloromethane at 25°C, over the whole concentration range. A comparative study is made between the primary and secondary amines and their mixtures with chloroalkanes. The applicability of the so-called ERAS model for predicting thermodynamic excess properties is tested here for excess molar volumes; the calculated values agree quite well with experimental data.     

Volumes and heat capacities of water andN-methylformamide in mixtures of these solvents

The densities of mixtures ofN-methylformamide (NMF) and water (W) have been measured at 5, 15, 25, 35, and 45°C, and the heat capacities of the same system at 25°C, both over the whole mole-fraction range. From the experimental data the apparent molar volumes (_v) and heat capacities (_c) of NMF and of water are evaluated. The relatively small difference between the partial molar volumes or heat capacities at infinite dilution and the corresponding molar volumes or heat capacities of the pure liquids for both NMF and water suggests that with regard to these quantities replacement of a NMF molecule by a water molecule or vice versa produces no drastic changes. The partial molar volume of water at infinite dilution in NMF is smaller than the molar volume of pure water, but the corresponding partial molar heat capacity is unexpectedly high.     

Ultrasonic and Volumetric Studies of Molecular Interactions in Acetonitrile + 1‐Alkanol (C6, C8, C10) Binary Liquid Mixtures at Different Temperatures

The densities, ρ, and ultrasonic speeds, u, have been measured in the binary liquid mixtures of acetonitrile (ACN) with 1‐hexanol, 1‐octanol and 1‐decanol, and in the pure components, as a function of composition at 25, 30, 35, 40 and 45 °C. The deviations in isentropic compressibility, Δκ_s, excess molar volume, V^E, deviations in ultrasonic speed, Δu, apparent molar compressibility, K_?2, apparent molar volume, V_?2, partial molar compressibility, $ {\rm \bar K}^\circ _{\phi,2} $, and partial molar volume, $ {\rm \bar V}^\circ _2 $, of 1‐alkanols in ACN have been calculated from the experimental data of densities and ultrasonic speeds. The variations of these parameters with composition of the mixtures indicate that the structure‐breaking effect dominates over that of the hydrogen‐bonding effect between unlike molecules, suggesting that ACN‐alkanol interaction is weaker than ACN‐ACN and alkanol‐alkanol interactions, and that the interaction (ACN‐alkanol) follows the order: 1‐hexanol > 1‐octanol > 1‐decanol. The excess molar volume data have been analysed by using Flory and Prigogine‐Flory‐Patterson theories. Further, the ultrasonic speeds in these mixtures were theoretically calculated with the help of several theories and empirical relations using the pure component data. The validity and relative merits of these theories and relations have been discussed.