Solvation of the Electrolytic Components of Seawater

Afanasiev, V. N.; Ustinov, A. N.

doi:10.1007/s10953-007-9152-3

Cited by 16 publications

(14 citation statements)

References 9 publications

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“…On the other hand, the determination of densities and ultrasound velocities, yielding adiabatic compressibilities, κ S , via eq , is readily made with commercial instruments. This explains the relative proliferation of the earlier κ S data − and those of Afanasev and co-workers ,,− over κ T ones. The latter group of authors reported hydration numbers h from the adiabatic compressibilities of aqueous salt solutions that diminish with increasing concentrations of the solute, expressed as its mole fractions, x E , as follows: h = h ∞ nobreak0em0.25em⁡ exp ( − k x E ) However, the values at infinite dilution, h ∞ , are considerably larger, by factors from 2 to 9, than those obtained by various other methods, Table , and cannot be valid.…”

Section: Discussionmentioning

confidence: 79%

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Concentration Dependence of Ionic Hydration Numbers

Marcus

2014

J. Phys. Chem. B

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Isothermal compressibility data of 23 aqueous electrolyte solutions at 25 °C from the literature are used to calculate their hydration numbers, which diminish as the concentration increases. Their limit at very high concentration is near the "number of adsorption sites" of water molecules on the ions, obtained by the BET method. On the contrary, hydration numbers obtained from ultrasound speed measurements yielding isentropic compressibilities cannot be valid, being much too large at infinite dilution.

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Section: Discussionmentioning

confidence: 79%

“… a References , , , and . b References and . c Reference . d References and . The first entry is from the freezing point depression, the second from vapor pressures at 25 °C. e References and . f Reference . …”

Section: Discussionmentioning

confidence: 99%

Concentration Dependence of Ionic Hydration Numbers

Marcus

2014

J. Phys. Chem. B

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“…Such behavior of the stated quantities is presumably caused by the overlapping of hydration shells of ions with the increase of the salt concentration. 7,9,10 The dependence of hydration numbers on the solute concentration is described by an exponential function…”

Section: Investigation Of Electrolytes Up To the Complete Solvation L...mentioning

confidence: 99%

“…In one of the first papers, 8 it was shown that solvation numbers obtained by the adiabatic compressibility method may be in good agreement with the data of papers on neutron and X-ray scattering, but only if the measurements are made at comparable concentrations. An attempt has been made 9,10 to carry out ultrasound investigations at the molecular level and from the data on the speed of propagation of ultrasound, heat capacity, and density at different temperatures and concentrations to obtain information on volumetric compression caused by the ionÀsolvent interaction, hydration numbers dependent on the concentration, compressibility, and density of water in hydration shells, etc. The most complete list of data on the determination of hydration parameters of different ABSTRACT: A new theory of electrolyte and nonelectrolyte solutions has been developed which, unlike the DebyeÀH€ uckel method applicable for small concentrations only, makes it possible to estimate thermodynamic properties of a solution in a wide range of state parameters.…”

Section: Introductionmentioning

confidence: 99%

Solvation of Electrolytes and Nonelectrolytes in Aqueous Solutions

Afanas'ev

2011

J. Phys. Chem. B

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A new theory of electrolyte and nonelectrolyte solutions has been developed which, unlike the Debye-Hückel method applicable for small concentrations only, makes it possible to estimate thermodynamic properties of a solution in a wide range of state parameters. One of the main novelties of the proposed theory is that it takes into account the dependence of solvation numbers upon the concentration of solution, and all changes occurring in the solution are connected with solvation of the stoichiometric mixture of electrolyte ions or molecules. The present paper proposes a rigorous thermodynamic analysis of hydration parameters of solutions. Ultrasound and densimetric measurements in combination with data on isobaric heat capacity have been used to study aqueous solutions of electrolytes NaNO3, KI, NaCl, KCl, MgCl2, and MgSO4 and of nonelectrolytes urea, urotropine, and acetonitrile. Structural characteristics of hydration complexes have been analyzed: hydration numbers h, the proper volume of the stoichiometric mixture of ions without hydration shells V(2h), compressibility β(1h), and the molar volume of water in hydration shells V(1h), their dependencies on concentration and temperature. It has been shown that for aqueous solutions the electric field of ions and molecules of nonelectrolytes has a greater influence on the temperature dependence of the molar volume of solution in hydration shells than a simple change of pressure. The cause of this effect may be due to the change in the dielectric permeability of water in the immediate vicinity of hydrated ions or molecules. The most studied compounds (NaCl, KCl, KI, MgCl2) have been studied in a wider range of solute concentrations of up to 4-5 mol/kg. Up to the complete solvation limit (CSL), the functions V(1h) = f(T) and β(1h) = f(T) are linear with a high correlation factor, and the dependence Y(K,S) = f(β1V1*) at all investigated concentrations of electrolytes and nonelectrolytes up to the CSL enables h and β(h)V(h) to be determined on the basis of relationships obtained in the study. The behavior of nonelectrolyte solutions is no different from that of electrolyte solutions, although it is possible to trace the difference between hydrophobic and hydrophilic interactions.

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“…The analysis of data on the compressibility of solutions, as it was shown in our previous publications [6,7], demonstrated that the change of solvation number h with concentration x 2 up to the concentrations corresponding to complete solvation limit (CSL) is described by…”

Section: Resultsmentioning

confidence: 77%