Tracer-diffusion of H₂ ³²PO₄ ^¯ Ions in Electrolyte Solutions in Agar Gel Medium

Abstract

The tracer-diffusion coefficients of H^'PO, ions have been determined in sodium and potassium nitrate solutions immobilized in 2.5 % agar gel over the concentration range 10"' -1.0 Μ at 298 K. Comparison of the experimental and theoretical values indicates failure of the Onsager-Fuoss theory at higher concentrations of electrolyte solutions. The observed results are explained on the basis of water-gel, ion-water and ion-ion interactions. Diffusion rates are also determined at various gel concentrations at different temperatures (298 -323 K), keeping the electrolyte (KNO,) concentration constant at 10"' M. The obstruction effect of gel calculated in terms of formation factor F is observed to increase with increasing gel concentration. The results are explained on the basis of EYRING's theory of diffusion. centage was varied from 0.5-5.0%, keeping the electrolyte concentration constant at 10" 2 M. After the gel had set, both ends of the tube were tightly corked and kept in an automatically regulated thermostat at the desired temperature.After allowing the diffusion to proceed for a definite time (24 hrs), the gel columns on both sides of the zone were sliced into 0.5 cm samples. These samples were carefully transferred to aluminium planchettes and dehydrated in a hot air oven at 65 °C. The radioactivity in each sample was counted by an end window Geiger-Muller counter under the conditions of constant geometry.