Diffusion measurements in aqueous L-ascorbic acid solutions

Diffusion coefficients in aqueous 0.05-1.0 M L-ascorbic acid solutions have been measured at 298.15 K by using a modified version of the Stokes diaphragm cell. The diffusion coefficient of un-ionized ascorbic acid molecule at zero concentration has been found to be 1.055 × 10-9 m2 s-1. The diffusion coefficient of an isolated ascorbate ion, C6H7O6-, is about 23 % lower than the molecular form; this indicates, as expected, that ions strongly interact with solvent molecules.