Densities and Molar Volumes of Aqueous Solutions of LiClO4 at Temperatures from 293 K to 343 K

Densities of aqueous solutions of purified lithium perchlorate at solute concentrations ranging from approximately 0.05 to 5 mol.kg(-1) have been measured by vibrating-tube densimetry at 5 K intervals over the temperature range 293 <= T/K <= 343 at atmospheric pressure. Apparent molar volumes of LiClO4(aq) derived from these data varied smoothly with solute concentration and temperature and could be fitted with an average precision of +/- 0.02 cm(3).mol(-1) using an extended Redlich-Rosenfeld-Meyer equation. The present results show that volumetric data listed in popular literature compilations are inaccurate. The effects of temperature on the partial molar volumes of LiClO4(aq) are nonlinear and indicate that the structure-breaking or-making character of this salt depends on concentration and temperature. Systematic differences observed between the volumes of lithium and sodium salts with a common anion appear to be related to differences in the strength of hydration of the two cations.