Abstract:dine reaction and a standard entropy change of £°= -8.0 cal./mole. Thus the present results by the n.m.r. method are quite consistent with the earlier work of Vinogradov and Linnell3 who obtained for this reaction a AH of -3.8 ± 0.2 kcal. from calorimetric measurements and an equilibrium constant of 22 ±3 at 30°from infrared measurements in CCU solutions.The significance of the variation of calculated " with temperature is uncertain. Temperature dependent n.m.r. effects, however, frequently indicate associatio… Show more
“…For calculation of the values for activity coefficient of NaCl in pure methanol from eq 8, it was assumed that the short-range contribution to the values of activity coefficient of NaCl in pure methanol is the same as that of pure water as solvent. Perhaps the disagreement of the values for activity coefficients of NaCl in pure methanol from this study (eq 8) with the corresponding experimental values of Gladden and Fanning is the result of this assumption. However, Kamps used an extension of Pitzer’s equation for the excess Gibbs energy of aqueous electrolyte solutions, parameters for which were fitted to the experimental data for the osmotic coefficient which in turn were calculated from vapor pressure measurements (0.04 < m < 0.22).…”
Section: Calculations and Resultscontrasting
confidence: 67%
“…The calculated activity coefficients of sodium chloride in (0.5 w/w) methanol/water mixed solvent systems at all concentrations (0 ≤ m ≤ m sat ) are given in Figure c. The stoichiometric activity coefficients of NaCl in methanol/water mixed solvents at 298.15 K are compared with the available literature data − in Figure . The values for activity coefficients of NaCl in pure methanol at 298.15 K from this study (eq 8) disagree with the corresponding values reported by Kamps, and both sets of data disagree with the activity coefficient data of Gladden and Fanning at higher concentrations (Figure d).…”
Section: Calculations and Resultsmentioning
confidence: 99%
“…The stoichiometric activity coefficients of NaCl in methanol/water mixed solvents at 298.15 K are compared with the available literature data − in Figure . The values for activity coefficients of NaCl in pure methanol at 298.15 K from this study (eq 8) disagree with the corresponding values reported by Kamps, and both sets of data disagree with the activity coefficient data of Gladden and Fanning at higher concentrations (Figure d). For calculation of the values for activity coefficient of NaCl in pure methanol from eq 8, it was assumed that the short-range contribution to the values of activity coefficient of NaCl in pure methanol is the same as that of pure water as solvent.…”
The unified theory of electrolytes (J. Phys. Chem. B 2009, 113, 2398-2404) for predicting the standard state thermodynamic properties of aqueous electrolytes has been extended to include mixed solvent systems. The solubility of solid sodium chloride in mixed solvents (methanol/water concentration up to 75% w/w) was also measured up to 466 K and pressures near 7 MPa. The present model, together with a simple modification of Pitzer's thermodynamic treatment of aqueous solutions, allows a priori prediction of solubility of electrolytes in aqueous/organic systems to extreme temperatures and pressures. Solubility is predicted for sodium chloride and potassium chloride in mixed solvents (methanol/water, ethanol/water) over a wide range of temperatures and compositions from the extension of the unified theory of electrolytes to mixed solvents. Comparisons indicate good agreement in all cases to well within the uncertainties of the experimental data. The stoichiometric activity coefficients of saturated solution of sodium chloride in methanol/water mixed solvents were calculated up to 473.15 K. The stoichiometric activity coefficients, as a function of temperature at all concentrations (0 ≤ m ≤ m(sat)) and the entire range of mole fraction of methanol, were also calculated up to 473.15 K. The novelty of the present approach is that no additional parameters are required to account for the medium effect.
“…For calculation of the values for activity coefficient of NaCl in pure methanol from eq 8, it was assumed that the short-range contribution to the values of activity coefficient of NaCl in pure methanol is the same as that of pure water as solvent. Perhaps the disagreement of the values for activity coefficients of NaCl in pure methanol from this study (eq 8) with the corresponding experimental values of Gladden and Fanning is the result of this assumption. However, Kamps used an extension of Pitzer’s equation for the excess Gibbs energy of aqueous electrolyte solutions, parameters for which were fitted to the experimental data for the osmotic coefficient which in turn were calculated from vapor pressure measurements (0.04 < m < 0.22).…”
Section: Calculations and Resultscontrasting
confidence: 67%
“…The calculated activity coefficients of sodium chloride in (0.5 w/w) methanol/water mixed solvent systems at all concentrations (0 ≤ m ≤ m sat ) are given in Figure c. The stoichiometric activity coefficients of NaCl in methanol/water mixed solvents at 298.15 K are compared with the available literature data − in Figure . The values for activity coefficients of NaCl in pure methanol at 298.15 K from this study (eq 8) disagree with the corresponding values reported by Kamps, and both sets of data disagree with the activity coefficient data of Gladden and Fanning at higher concentrations (Figure d).…”
Section: Calculations and Resultsmentioning
confidence: 99%
“…The stoichiometric activity coefficients of NaCl in methanol/water mixed solvents at 298.15 K are compared with the available literature data − in Figure . The values for activity coefficients of NaCl in pure methanol at 298.15 K from this study (eq 8) disagree with the corresponding values reported by Kamps, and both sets of data disagree with the activity coefficient data of Gladden and Fanning at higher concentrations (Figure d). For calculation of the values for activity coefficient of NaCl in pure methanol from eq 8, it was assumed that the short-range contribution to the values of activity coefficient of NaCl in pure methanol is the same as that of pure water as solvent.…”
The unified theory of electrolytes (J. Phys. Chem. B 2009, 113, 2398-2404) for predicting the standard state thermodynamic properties of aqueous electrolytes has been extended to include mixed solvent systems. The solubility of solid sodium chloride in mixed solvents (methanol/water concentration up to 75% w/w) was also measured up to 466 K and pressures near 7 MPa. The present model, together with a simple modification of Pitzer's thermodynamic treatment of aqueous solutions, allows a priori prediction of solubility of electrolytes in aqueous/organic systems to extreme temperatures and pressures. Solubility is predicted for sodium chloride and potassium chloride in mixed solvents (methanol/water, ethanol/water) over a wide range of temperatures and compositions from the extension of the unified theory of electrolytes to mixed solvents. Comparisons indicate good agreement in all cases to well within the uncertainties of the experimental data. The stoichiometric activity coefficients of saturated solution of sodium chloride in methanol/water mixed solvents were calculated up to 473.15 K. The stoichiometric activity coefficients, as a function of temperature at all concentrations (0 ≤ m ≤ m(sat)) and the entire range of mole fraction of methanol, were also calculated up to 473.15 K. The novelty of the present approach is that no additional parameters are required to account for the medium effect.
“…As can be seen from Figure , the activity coefficients calculated from the data by Yan et al are nicely represented (average relative deviation = 2.4%), whereas the ones calculated from the data by Gladden and Fanning 115 are not consistent with the data reported by Barthel et al (The data of Gladden and Fanning, also at other temperatures, were therefore discarded in the present work.) 2 Mean ionic activity coefficient of NaCl in CH 3 OH at 298.15 K: (□) Gladden and Fanning; (·) Yan et al; () prediction, this work.…”
Section: Modelingmentioning
confidence: 74%
“…The mean ionic activity coefficient of sodium chloride in methanol (on the molality scale) is where Gladden and Fanning as well as Yan et al reported some emf data for methanolic solutions containing sodium chloride at T = 298.15 K. These data have been reevaluated; i.e., the standard electrode potentials were recalculated by means of the usual extrapolation procedureusing Pitzer's modified Debye−Hückel term as used hereand the mean ionic activity coefficients of sodium chloride were redetermined by using those (slightly different numbers for the) standard electrode potentials. As can be seen from Figure , the activity coefficients calculated from the data by Yan et al are nicely represented (average relative deviation = 2.4%), whereas the ones calculated from the data by Gladden and Fanning 115 are not consistent with the data reported by Barthel et al (The data of Gladden and Fanning, also at other temperatures, were therefore discarded in the present work.)…”
A model for the Gibbs excess energy of mixed-solvent (chemical-reacting) electrolyte systems is presented. The activities of solvent and solute species are calculated by applying a new extension of Pitzer's equation for the excess Gibbs energy of aqueous electrolyte solutions, which allows for solvent mixtures. The capability of the new model to simultaneously describe such properties as, e.g., the mean ionic activity coefficient and the solubility of a salt (for example, sodium chloride) in a binary solvent mixture (for example, methanol + water), as well as the influence of that salt on the vapor-liquid equilibrium of that binary solvent mixture, is tested. The new model gives an explanation for the "salting-out" and "salting-in" effects resulting, e.g., from the addition of a salt to a liquid mixture of volatile solvents. The new model can also be applied to describe the gas solubility in mixed solvents in the presence of electrolytes. The capability of the new model to describe the solubility of a single gas in a binary solvent mixture is tested by dealing with the solubility of carbon dioxide in aqueous solutions of methanol over the whole range of solvent composition, i.e., from pure water to pure methanol.
The solvation behavior of various silver(I) salts, viz. silver (I) iodate, bromate and sulfate in iso‐dielectric solvent mixtures of methanol and N‐methyl‐2‐pyrrolidinone (NMP) has been investigated using Gibbs transfer energies and solvent transport number measurements. The Gibbs transfer energies of the salts were split into their individual ionic contributions using both negligible liquid junction potential method (nLJP) and the reference electrolyte method using tetraphenylarsonium tetraphenylborate (TATB). The results show a significant hetero‐selective solvation of all salts beyond XNMP = 0.5 with silver ion being selectively solvated by NMP and the anions by methanol.
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