The strength of acids in alcohols as determined by steady-state voltammetry

Steady-state voltammograms for reduction of acids of various strengths in a lcohols with excess supporting electrolyte and without any supporting elect rolyte can be used to infer charge type and strength of the acid on the bas is of the phenomenon of migration. For strong and moderately weak acids (K- a/G(HA)(a) > 10(-3)) in alcohols, the ratio of steady-state transport-limit ed current to diffusion-limited current, corrected appropriately for ion-io n interactions, the presence of ionic impurities, and changes in viscosity, for hydrogen ion reduction without supporting electrolyte acid with excess supporting electrolyte equals 2, For acetic acid, which is very weak (K-a/ G(HA)(a) < 10(-6)), the value of the steady-state transport-limited current is, under the. experimental conditions applied here, independent :of;suppo rting electrolyte concentration. In the case of a homogeneous acid-base equ ilibrium, a novel analytical procedure yields diffusion coefficients of bot h hydrogen ion and undissociated weak acid molecules from the diffusional a nd migrational currents. Limiting currents obtained in alcohols with excess supporting electrolyte and without supporting electrolyte are compared by means of an extended formula that incorporates the ionic strength dependenc e of diffusion coefficients.