Apparent molar volumes of multiply charged electrolytes

Abstract

The apparent molar volumes of K₄Mo(CN)₈, K₃Cr(C₂O₄)₃, Ca₂Fe(CN)₆, LaFe(CN)₆ and K₄Zr(C₂O₄)₄ were measured using a pycnometric and dilatometric methods at 25 and 3.39°C. At 25°C K₄Mo(CN)₈ follows accurately, K₃Cr(C₂O₄)₃ and LaFe(CN)₆ follow approximately the Debye–Hückel limiting law at high dilution. K₄Zr(C₂O₄)₄ shows very large deviations, probably due to chemical equilibria. At 3.39°C all the salts show positive deviations from the Debye–Hückel limiting law even at the lowest concentrations and have V₀ values considerably smaller than at 25°C. This is considered as evidence that solute–solvent interactions are important in determining both V₀ and the change of ϕ_v with the concentration.