Apparent Molal Volumes of Aqueous Monovalent Salt Solutions at Various Temperatures

A precision magnetic float densitometer has been used to measure the densities of 0.1 molal LiCl, NaCl, KCl, RbCl, CsCl, NaF, KBr, Kl, and KNO₃ aqueous salt solutions at one-degree intervals from 20° to 40° C. The densities have been fit to an equation of the form, d_soin = A + Bt + Ct² + Dt³ with a maximum root-mean-square deviation of 4 p.p.m. The apparent molal volume, ϕv, and the apparent molal expansibility, ϕe, have been calculated for these solutions from the density data. The values obtained agree very well with those from the literature. The apparent molal expansibilities for these solutions, ϕe, have been equated to the infinite dilution values-i.e., ϕe = Ē°. The contributions to Ē° (salt) have been divided into ionic contributions. The expansibilities for the cations decrease in the order Na⁺>K⁺>Rb-Cs⁺>H⁺>Li⁺ and the expansibilities for the anions increase in the order F^- <Cl^--Br^- < I^- < NO₃^-.