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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, C pϕ. 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, C pϕ o, for each salt. The C pϕ 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 C pϕ o 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.

The morphology of precipitated calcium carbonate is a function of conductivity.