Reference electrodes, liquid - junction potential, indicator electrodes,. As the main contents of the document "Chapter 6: Electrodes and Potentiometry". Invite you to consult the text book for more documents serving the academic needs and research. | Figure 6-3 shows a very simple liquid junction consisting of a 1M hydrochloric acid solution that is in contact with a solution that is in that acid. An inert porous barrier, such as a fritted glass plate, prevents the two solutions from mixing. Both hydrogen and chloride ions tend to difuse across this boundary from the more concentrated to the more dilute solution. The driving force for each ion is proportional to the activity difference between solutions. In the present sample, hydrogen ions diffuse more rapidly than chloride ions, and, as shown in the figure, a separation of charge results. The more dilute side of the boundary becomes positively charged because of the more diffusion of hydrogen ions. The concentrated side therefore acquired a negative charge from the excess of slower moving chloride ions. The charge developed tends to counteract the differences in diffusion rates of the two ions so that a condition of equilibrium is attained rapidly. The potential difference resulting from this charge separation may be several hundredths of a volt.
