Densities and Apparent Molar Volumes of Rubidium and Cesium Triflates to High Concentrations in Aqueous Solution at Temperatures from 293.15 to 343.15 K

Densities of aqueous solutions of rubidium triflate (RbTf) and cesium triflate (CsTf), where Tf– is the trifluoromethanesulfonate ion (CF3SO3 –), have been measured by vibrating-tube densimetry at temperatures from 293.15 to 343.15 K at 5 K intervals. Concentrations ranged from 0.03 to 5.0 mol·kg–1...

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Bibliographic Details
Published in:Journal of chemical and engineering data Vol. 67; no. 1; pp. 123 - 131
Main Authors: Hnedkovsky, Lubomir, Hefter, Glenn
Format: Journal Article
Language:English
Published: American Chemical Society 13-01-2022
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Summary:Densities of aqueous solutions of rubidium triflate (RbTf) and cesium triflate (CsTf), where Tf– is the trifluoromethanesulfonate ion (CF3SO3 –), have been measured by vibrating-tube densimetry at temperatures from 293.15 to 343.15 K at 5 K intervals. Concentrations ranged from 0.03 to 5.0 mol·kg–1 for RbTf and from 0.02 to 3.9 mol·kg–1 for CsTf. No volumetric data for either salt appear to have been published previously. Apparent molar volumes (V ϕ) calculated from the densities were well modeled with Pitzer equations. Standard partial molar volumes, V o, for RbTf­(aq) and CsTf­(aq) were determined by extrapolation of the Pitzer fits to infinite dilution. Isobaric coefficients of thermal expansion (expansivities), α, derived from the temperature dependence of the densities, increased with concentration, especially at lower T, consistent with the solvent-structure-breaking character of their component ions. Combination of the present V o values with a common extra-thermodynamic assumption and relevant literature data provided ionic volumes, V o(Rb+,aq) and V o(Cs+,aq), that show more realistic temperature dependences than previous estimates.
ISSN:0021-9568
1520-5134
DOI:10.1021/acs.jced.1c00837