Solvation of Fluoride Ions. II. Enthalpies and Entropies of Transfer From Water to Aqueous Methanol

1988 ◽  
Vol 41 (12) ◽  
pp. 1971 ◽  
Author(s):  
GT Hefter ◽  
PJ Mclay
Keyword(s):  
Composition Range ◽  
Potassium Fluoride ◽  
Alkali Metal Ions ◽  
Halide Ions ◽  
Aqueous Methanol ◽  
Fluoride Ions ◽  
Solvent Interactions ◽  
Enthalpies Of Transfer ◽  
Complex Dependence ◽  
The Individual

Enthalpies of transfer of potassium fluoride from water to water-methanol mixtures over the whole composition range have been determined by calorimetry. Combination of these values with literature data has enabled calculation of the enthalpies and entropies of transfer for the individual ions through the tetraphenylarsonium tetrapbenylborate ( tatb ) assumption. The values of ΔtH°(F-) and ΔtS°(F-) show a complex dependence on solvent composition which closely parallels the dependence of the other halide ions. These effects are discussed in terms of ion-solvent and solvent-solvent interactions. The halide ions appear to be (weakly) preferentially solvated by H2O, and the alkali metal ions by MeOH.

Kinetics and Mechanism of Decomposition of 1,3-Bis(4-methylphenyl)triazene Catalyzed with Substituted Benzoic Acids in 25% Aqueous Methanol-General or Specific Catalysis?

1994 ◽  
Vol 59 (9) ◽  
pp. 2029-2041
Author(s):  
Oldřich Pytela ◽  
Taťjana Nevěčná
Keyword(s):  
Benzoic Acids ◽  
Hammett Equation ◽  
Aqueous Methanol ◽  
Mechanism Of Decomposition ◽  
Kinetics Of Decomposition ◽  
Independent Variable ◽  
Amino Derivatives ◽  
Substituted Benzoic Acids ◽  
The Individual ◽  
Kinetics Of

The kinetics of decomposition of 1,3-bis(4-methylphenyl)triazene catalyzed with 13 substituted benzoic acids of various concentrations have been measured in 25 vol.% aqueous methanol at 25.0 °C. The rate constants observed (297 data) have be used as values of independent variable in a series of models of the catalyzed decomposition. For the catalytic particles were considered the undissociated acid, its conjugated base, and the proton in both the specific and general catalyses. Some models presumed formation of reactive or nonreactive complexes of the individual reactants. The substituent effect is described by the Hammett equation. The statistically best model in which the observed rate constant is a superposition of a term describing the dependence on proton concentration and a term describing the dependence on the product of concentrations of proton and conjugated base is valid with the presumption of complete proton transfer from the catalyst acid to substrate, which has been proved. The behaviour of 4-dimethylamino, 4-amino, and 3-amino derivatives is anomalous (lower catalytic activity as compared with benzoic acid). This supports the presumed participation of conjugated base in the title process.

Transfer Thermodynamic Functions ∆Gt0, ∆Ht0 and T∆St0 of cis- and trans-[CoCl2(en)2]+ Isomers in Aqueous Mixtures of Methanol, tert-Butyl Alcohol and Acetonitrile

2000 ◽  
Vol 65 (9) ◽  
pp. 1455-1463
Author(s):  
Oľga Vollárová ◽  
Ján Benko
Keyword(s):  
Enthalpy Of Solution ◽  
Transfer Functions ◽  
Partial Molar Volumes ◽  
Butyl Alcohol ◽  
Aqueous Mixtures ◽  
Aqueous Methanol ◽  
Solvent Interactions ◽  
Tert Butyl Alcohol ◽  
Surface Charge Distribution ◽  
Cis And Trans

The solubility, partial molar volume and standard integral molar enthalpy of solution of cis- and trans-[CoCl2(en)2]Cl in water, aqueous methanol, aqueous tert-butyl alcohol and aqueous acetonitrile are reported. The transfer functions ∆Gt0, ∆Ht0 and T∆St0 as well as partial molar volumes are used to obtain information on the solute-solvent interactions. Results obtained are discussed in terms of differences in the surface charge distribution in isomeric coordination species.

scholarly journals Density and Viscosity of LiCl, LiBr, LiI and Kcl in Aqueous Methanol at 313.15K

2021 ◽  
Vol 37 (5) ◽  
pp. 1083-1090
Author(s):  
V. V. Kadam ◽  
A. B. Nikumbh ◽  
T. B. Pawar ◽  
V. A. Adole
Keyword(s):  
Experimental Data ◽  
Dielectric Constant ◽  
Apparent Molar Volumes ◽  
Strong Electrolyte ◽  
Aqueous Methanol ◽  
Molar Volumes ◽  
Solvent Interactions ◽  
Viscosity Coefficients ◽  
Physicochemical Processes ◽  
Increase With Increase

The densities and viscosities of electrolytes are essential to understand many physicochemical processes that are taking place in the solution. In the present research, the densities and viscosities of lithium halides, LiX (X = Cl, Br, I ) and KCl in (0, 20, 40, 50, 60, 80 and 100) mass % of methanol + water at 313.15K were calculated employing experimental densities (ρ), the apparent molar volumes( ϕv) and limiting apparent molar volumes (0v) of the electrolytes. The (0v) of electrolyte offer insights into solute-solution interactions. In terms of the Jones-Dole equation for strong electrolyte solution, the experimental data of viscosity were explored. Viscosity coefficients A and B have been interpreted and discussed. The B-coefficient values in these systems increase with increase of methanol in the solvents mixtures. This implied that when the dielectric constant of the solvent decreases, so do the solvent-solvent interactions in these systems.

Molar volumes and refractivities of highly concentrated solutions of ammonium and potassium thiocyanates in water and dimethylsulphoxide

1988 ◽  
Vol 66 (9) ◽  
pp. 2244-2249 ◽  
Author(s):  
Petr Pacák ◽  
Zdenĕk Kodejš
Keyword(s):  
Composition Range ◽  
Apparent Molar Volumes ◽  
Refractive Indices ◽  
Dilute Solutions ◽  
Concentrated Solutions ◽  
Lorenz Equation ◽  
Molar Volumes ◽  
Solvent Interactions ◽  
Density Measurements ◽  
Concentration Dependences

Densities and refractive indices of highly concentrated solutions of ammonium and potassium thiocyanates in water and dimethylsulphoxide have been measured at 333.2 K in the composition range from xs = 0.01 up to saturated solutions. Molar volumes and apparent molar volumes have been calculated from density measurements and their concentration dependences are discussed. All the systems are volumetrically non-ideal and exhibit negative deviations from additivity. The molar refractivities were calculated from the refractive indices using the Lorentz–Lorenz equation. The refractivity values of individual ions were estimated in infinitely dilute solutions and were used for discussion of ion–solvent interactions.

Ion–ion–solvent interactions in aqueous ionic cosolvent systems. III. Thermodynamics of hydrogen bromide and hydrogen iodide from water to aqueous solutions of sodium nitrate from emf measurements at different temperatures and the structuredness of the solvents

1987 ◽  
Vol 65 (12) ◽  
pp. 2843-2848
Author(s):  
Sibaprasad Rudra ◽  
Himansu Talukdar ◽  
Kiron K. Kundu
Keyword(s):  
Sodium Nitrate ◽  
Structural Changes ◽  
Hydrogen Bromide ◽  
Scaled Particle Theory ◽  
Relative Order ◽  
Emf Measurements ◽  
Solvent Interactions ◽  
Different Temperatures ◽  
Composition Profiles ◽  
The Individual

Standard free energies [Formula: see text] and entropies [Formula: see text] of transfer of hydrogen bromide and iodide from water to the aqueous 1, 2, and 4 m of sodium nitrate have been determined by measuring the emf's of the cell: Pt, H2(g, 1 atm)/KOH(m1), KX(m2), solvent/AgX–Ag where X = Br or I at five equidistant temperatures ranging from 15–35°C. [Formula: see text] values of HBr, HI as well as that of HCl obtained from earlier paper and particularly of the individual ions [Formula: see text](i), obtained by use of modified TATB assumption reported earlier and also [Formula: see text](i) obtained after correcting for "cavity" effect and Born-type electrostatic effect estimated tentatively by the scaled particle theory (SPT) and simple Bom equation, respectively, reveal the relative order of stabilisation of Cl−, Br−, and I− ions. Analysis of [Formula: see text]–composition profile (X = Cl, Br, and I) exhibits a characteristic "maxima" around 1.5 m NaNO3 with the relative order HI > HBr > HCl in the region of maxima. Moreover, dissection of [Formula: see text] values into the individual ion contributions by use of the modified TATB assumption reported earlier, results in the characteristic "maxima" around 1.5 m NaNO3 in [Formula: see text] or [Formula: see text]–composition profiles for H+ and "minima" for Cl−, Br−, and I−. The results are discussed in terms of ion–ion–solvent interactions as well as the structural changes of the solvents.

Free energies and entropies of transfer of hydrogen halides from water to aqueous 2-methoxy ethanol and structuredness of the solvents

1985 ◽  
Vol 63 (4) ◽  
pp. 798-803 ◽  
Author(s):  
Prabir K. Guha ◽  
Kiron K. Kundu
Keyword(s):  
Dielectric Constant ◽  
Mixed Solvents ◽  
Three Dimensional ◽  
Halide Ions ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Hydrogen Halides ◽  
Emf Measurements ◽  
Composition Profiles ◽  
The Individual

Standard free energies (ΔGt0) and entropies (ΔSt0) of transfer of HBr and HI from water to some aqueous solutions of 2-methoxy ethanol (ME) have been determined from emf measurements of the cells: Pt, H2 (g, 1 atm)/HBr (m), solvent/AgBr–Ag and Pt, H2 (g, 1 atm)/KOH (m1), KI (m2), solvent/AgI–Ag, respectively, at seven equidistant temperatures ranging from 15 to 45 °C. ΔGt0 values of HBr and HI as well as of HCl obtained from literature, and particularly that of the individual ions obtained by tetraphenylarsonium tetraphenylboron (TATB) assumption, suggest that while H+ is increasingly stabilized by cosolvent-induced larger "basicity", halide ions (X−) are increasingly destabilized by cosolvent-induced decreased "acidity" and the dielectric constant of the mixed solvents compared to that of water. Analysis of the variation of the observed TΔSt0(HX) and particularly of ΔY (= TΔSt0(H+) + TΔS0t.ch (X−), with composition, in the light of Kundu etal's semi-quantitative theory reveals that ME induces breakdown of three dimensional (3D) tetrahedral structures of water at water-rich compositions. This is being followed by an ordered region due to possible H-bonded cosolvent–water complexation and then the usual disordered region due to packing imbalance. Comparison of ΔY(HI)–composition profiles for aqueous mixtures of t-butanol (ButOH), ethylene glycol (EG), and 1,2-dimethoxy ethane (DME) also demonstrates that the remarkable enhancement of 3D water structures by the well known structure promoter ButOH gets succintly diminished when cosolvent ButOH is replaced by EG, ME, and DME, as is expected from structural and electronic considerations of the cosolvents.

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