Transference numbers and phenomenological transport coefficients for concentrated aqueous hydrochloric acid solutions at 25�C

Abstract

The transference numbers of HCl in water at 25°C have been determined up to 8 mol-kg−1 by using cells with transference. The problem of the solubility of AgCl from Ag/AgCl electrodes was avoided by employing dilute chlorine gas/iridium electrodes for T H and hydrogen gas/platinum electrodes for T Cl . The sums of the independently measured T H and T Cl values never differed from unity by more than 0.9%. The cation constituent transference number of HCl was also measured at 1M by the recently modified moving boundary method, but at higher concentrations the Soret effect produced unacceptably large current dependences. Combination of these transference numbers with literature conductances, diffusion coefficients and activity coefficients led to a new set of phenomenological transport coefficients l ij . The resulting curve for l12/c vs. c behaves more normally than did the curve based on previous transference numbers.