Tracer diffusion of sodium-22 chloride in MgCl2-H2O-solutions

The tracer diffusion coefficients of sodium-22 chloride were determined as function of magnesium chloride concentration in aqueous solutions at 25 deg rees C in a large concentration region. Closed capillary method was applied in these experiments. The optimal position of a quartz capillary with resp ect to the gamma sensitive scintillating detector was determined with a rad ioactive point source. Three different methods were statistically tested to calculate the tracer diffusion coefficients from the experimental pulse co unts as a function of time. The method leading to the most exact diffusion coefficient values was found. The Onsager limiting law (OLL) was verified t o the tracer diffusion of sodium-22 chloride. The departure from the OLL at concentration higher than 0.01 M is caused in part by the increase in visc osity of the supporting electrolyte.