Temperature Dependency Studies on Volumetric Change and Structural Interaction in Aqueous Rare Earth Nitrate Solution

Abstract

Densities and refractive indices of the aqueous solutions of lanthanum, samarium, cerium, europium, and praseodymium nitrate were determined at different temperatures ranging from 293.15 to 343.15 K and atmospheric pressure, with the molality ranging from ~0.0002 to ~1.5 mol·kg−1. From these density values, the apparent molal volume was calculated and correlated with the Meyer–Seaders equation and the temperature dependence of density was correlated by a second order polynomial. From the correlation, the apparent molal volumes at infinite dilution were estimated to give an idea of the structural interactions occurring in the solutions. The cubic expansion coefficient and the variation of isobaric heat capacity with pressure at different temperatures were calculated from the volumetric measurements. The measurements were performed as per ASTM procedures. The volumetric properties provide information on ion–ion and ion–solvent interactions. A comparison has been made for the experimental values with those of literature, if available. The dependency of volume on concentration provides an insight into long range electrostriction of water by the ions.