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Heat Capacities of Aqueous Solutions of K4Fe(CN)6, K3Fe(CN)6, K3Co(CN)6, K2Ni(CN)4, and KAg(CN)2 at 298.15 K

Kianinia, Y., Hnědkovský, L., Senanayake, G., Akilan, C., Khalesi, M.R., Abdollahy, M., Darban, A.K. and Hefter, G. (2018) Heat Capacities of Aqueous Solutions of K4Fe(CN)6, K3Fe(CN)6, K3Co(CN)6, K2Ni(CN)4, and KAg(CN)2 at 298.15 K. Journal of Chemical & Engineering Data, 63 (5). pp. 1773-1779.

Link to Published Version: https://doi.org/10.1021/acs.jced.8b00078
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Abstract

Isobaric volumetric heat capacities of aqueous solutions of K4Fe(CN)6, K3Fe(CN)6, K3Co(CN)6, K2Ni(CN)4, and KAg(CN)2 have been measured at 298.15 K over the approximate concentration range 0.02 to 0.4 mol·kg–1 using a Picker flow calorimeter. These data were combined with measured densities to calculate the corresponding apparent molar isobaric heat capacities, Cpϕ. The values so obtained were fitted as a function of concentration using an extended Redlich–Rosenfeld–Meyer-type equation to provide the standard state (infinite dilution) quantities, Cpϕo, for each salt. The Cpϕ values for all the salts studied showed similar dependences on concentration, with a slight upward curvature at higher molalities, possibly due to anion aggregation. Values of Cpϕo for the aquated cyanometallate anions were estimated using the tetraphenylphosphonium tetraphenylborate extrathermodynamic assumption and were little affected by ion size but were strongly dependent on ionic charge, ranging from −191 J·K–1·mol–1 for [Fe(CN)6]4–(aq) to +178 J·K–1·mol–1 for [Ag(CN)2]−(aq). This indicates that the differences between the anions are mostly due to their effect on the surrounding water molecules.

Publication Type: Journal Article
Murdoch Affiliation: School of Engineering and Information Technology
Publisher: American Chemical Society
Copyright: © 2018 American Chemical Society
URI: http://researchrepository.murdoch.edu.au/id/eprint/41013
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