Densities and apparent molar volumes of aqueous NaCl–KBr mixtures at 298.15 K. An alternative treatment

Abstract

In estimating properties of mixtures of electrolytes from those of the individual components, it is better to calculate the density directly using a mixing rule, rather than from the derived quantity, the apparent molar volume. Each component contributes to the density in proportion to its ionic strength fraction in the mixture; this simple mixing rule gives better agreement for NaCl–KBr mixtures than do Pitzer's equations, incorporating up to sixteen parameters. Some discrepancies in Kumar's published data (Can. J. Chem. 63, 3200 (1985)) on NaCl–KBr mixtures are discussed.