Mutual diffusion coefficients of SrCl2–H2O and CsCl—H2O at 25 °C from Rayleigh interferometry

Volume-fixed mutual diffusion coefficients of aqueous NaI have been measured from low concentrations to 10.8 mol-(kg H2O)−1 (7.6 mol-dm−3), and those of LiCl up to 1.6 mol-(kg H2O)−1 (1.55 mol-dm−3), at 25°C using free-diffusion Rayleigh interferometry. The accuracy of these diffusion coefficients is 0.1−0.2%. LiCl-H2O has some of the lowest diffusion coefficients for alkali halides, whereas NaI-H2O has some of the highest. The significance of these differences is briefly discussed.