Diffusion and the bi-ionic potential with an ion exchanger membrane

Abstract

The potential between two silver-silver bromide electrodes in 0.01 m HBr and NaBr separated by a cation exchanger membrane was studied for several hundred hours. After stirring there was a rapid decrease to a minimum at 20 minutes, then a rise to a maximum at 400 minutes, followed by a slow, almost linear decrease which extrapolated at zero time to only 1 mv. lower than the value with solutions flowing. This decrease is probably caused by the activity gradients shifting from the membrane to the liquid solutions. It is suggested that the earlier changes may be explained by gradients shifting from the transition layer to the liquid and then from the membrane to the transition layer, and that the more transient effects which are sometimes observed may be explained by lags in the dissipation of heat.