VOLUMETRIC PROPERTIES OF ALKALI METAL P-TOLUENESULPHONATES IN WATER AS A FUNCTION OF TEMPERATURE

C. Pohar and S. Skale Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia

ABSTRACT

Density data are presented for alkaline salts of p-toluenesulphonic acid at temperatures from 5 to 40 ^OC up to concentrations of ~2 mol/kg. The apparent molar volumes, V2F, were calculated for these solutions from the density measurements. The apparent molar volumes were fitted to the equation of Redlich and Meyer to determine two important parameters: i) the apparent molar volume at infinite dilution, V2Fo, and ii) the deviation constant bV. At 25 ^OC the additivity rule of the individual ionic contributions was confirmed. Further, V2Fo increases with increasing temperature for all the salts, while the parameters bV monotonically decrease from positive to negative values (in the order Li<Na<K<Rb<Cs) as the temperature is increased. The effect of temperature on the apparent molar volumes of the p-toluenesulphonates in water at infinite dilution is similar to that of other simple electrolytes.