Ion association and hydration in aqueous solutions of nickel(II) and cobalt(II) sulfate

Chen, Ting and Hefter, Glenn and Buchner, Richard (2005) Ion association and hydration in aqueous solutions of nickel(II) and cobalt(II) sulfate. JOURNAL OF SOLUTION CHEMISTRY, 34 (9). pp. 1045-1066. ISSN 0095-9782, 1572-8927

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Abstract

Aqueous solutions of nickel(II) and cobalt(II) sulfate have been investigated at 25 degrees C by dielectric relaxation spectroscopy (DRS) over a wide range of frequencies (0.2 <= nu(GHz) <= 89) and salt concentrations (0.025 <= c( mol-L-1) <= 1.4). The spectra indicate, as for MgSO4(aq) studied previously, the simultaneous presence of double solvent-separated, solvent-shared and contact ion pairs in both NiSO4(aq) and CoSO4(aq). The stepwise formation constants for each ion-pair type and the overall association constant, obtained from the data are in good agreement with ultrasonic relaxation and other estimates. The DR spectra at higher concentrations ( c >= 0.5 mol-L-1) suggest the existence of a nonlinear triple ion M2SO42+( aq). Consistent with the very strong hydration of the salts, which have 'effective' hydration numbers approaching 27 at infinite dilution, there are no significant differences in any of the relaxation or thermodynamic parameters for NiSO4( aq) and CoSO4( aq), except that the triple ion appears to be somewhat more stable for the latter.

Item Type: Article
Uncontrolled Keywords: FOLGE CHEMISCHER RELAXATION; DIELECTRIC-RELAXATION; POLAROGRAPHIC DETERMINATION; 2-2 ELECTROLYTES; WATER; DYNAMICS; COMPLEX; SCHALLABSORPTION; SPECTROSCOPY; 25-DEGREES-C; ion pairs; triple ions; nickel(II) sulfate; cobalt(II) sulfate; dielectric relaxation; aqueous solutions; ion association; ion hydration
Subjects: 500 Science > 540 Chemistry & allied sciences
Divisions: Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry VI - Physical Chemistry (Solution Chemistry) > PD Dr. Richard Buchner
Depositing User: Dr. Gernot Deinzer
Date Deposited: 30 Apr 2021 05:30
Last Modified: 30 Apr 2021 05:30
URI: https://pred.uni-regensburg.de/id/eprint/35704

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