Diffusion coefficient of iodide ions in aqueous medium and in vacuum: An appraisal

Diffusion coefficient of iodide ion was determined through cyclic voltammetric technique and compared with the values in literature. the contribution of (a) the fractal surface of the electrode,and (b) possible involvement of subsequent chemical reaction (ec) to the peak current affecting the diffusion coefficient were analyzed. it was concluded that the diffusion coefficient obtained via peak current of the cyclic voltammogram corrected for sweep dependence could be relied upon. the diffusion coefficient,d,of i- ion in aqueous media is deduced to be 1.95 (±0.05) ×10-5 cm2s-1. fractal analysis showed there is very negligible effect of fractal surface of the electrode. diffusion coefficient of iodide ion in vacuum was calculated from equation d = h / 4πmr,where h is planck's constant and mi-,is the mass of iodide ion. d of i- in vacuum came out to be much smaller,2.5 × 10-6 cm2s-1,as compared to the one in aqueous solution. this d may be considered as the lower limit of the diffusion coefficient of a species,here i-. © 2015,chemical society of pakistan. all rights reserved.