Determination of Activation Energy for the Diffusion of Fe3+ Ions in Agar Gel Medium Containing Various Transition Metal Sulfates

Abstract

The study of the diffusion of ferric ions in agar gel containing transition metal sulfates was carried out. The effect of gel concentration, electrolyte concentration and temperature on the diffusion of Fe3+ ions in various transition metal sulfates was studied with a view to verify Wang’s model of diffusion and the applicability of transition state theory to diffusion in a gel medium. The diffusion coefficients were measured using the zone diffusion technique. For a given concentration of electrolyte the activation energy (E) is found to decrease with an increase in the charge density of the cation of the supporting electrolyte and for a given system it is found to decrease with increasing electrolyte concentration in agreement with Wang’s model. This observation is explained on the basis of the distortion in the water structure caused by ions and agar molecules. At a given electrolyte concentration the magnitude of the Arrhenius parameters, E and Do, is found to decrease with increasing gel concentration in agreement with the transition state theory of diffusion.