Apparent molal volumes of KCN, K2Zn(CN)4 and K2Cd(CN)4 in aqueous solutions at 15–45°C. Effect of ionization and hydrolysis

Abstract

The apparent molal volumes, ϕ_v of KCN (0.001 < c < 1 mol dm^–3), K₂Zn(CN)₄ and K₂Cd-(CN)₄(0.002 < c < 0.3 mol dm^–3) have been determined in aqueous solution at 15, 25, 35 and 45°C. In each case Debye–Hückel limiting law behaviour is not approached in the low concentration region and this anomalous behaviour is accounted for in terms of hydrolysis and ionization reactions of the solute species. The method used employs Young's mixture rule and yields infinite dilution volumes of each solute species. In other cases, expecially for high valence-type electrolytes, any observed deviations from Debye–Hückel limiting behaviour might be more simply explained in terms of solute chemical reaction.