Diffusion studies in aqueous solutions of sulfur dioxide

Abstract

Measurements of the over-all or effective diffusion coefficients of aqueous solutions of sulfur dioxide at 21°C have been made using 35S as tracer. The experiments were carried out over the concentration range (0·016–1·78)M. Also the effective diffusion coefficients of 0·2 M sulfur dioxide solutions in 3·5 M NaClO 4 medium have been measured at different pH values. The diffusion coefficients found here can not be ascribed to any one diffusing species but should be treated as concentration weighted means of the self-diffusion coefficients of the species found in the solutions. On the basis of the equilibrium constants for sulfur dioxide solutions in 3·5M NaClO 4 medium the concentration ratios of sulfur dioxide, hydrogen sulfite ions and sulfite ions and hence the over-all diffusion coefficient of the sulfur dioxide solutions are obtained as a function of pH. By fitting this equation to the experimental results the single diffusion coefficients of sulfur dioxide, hydrogen sulfite ions and sulfite ions are calculated.