SILVER – SILVER ION EXCHANGE REACTIONS

Abstract

The extent of the exchange between silver foils and silver ions in nitrate solution was compared with surface area measurements made by the Bowden-Rideal method. No quantitative correspondence between the two measurements was observed. During one hour the exchange with mechanically abraded surfaces affected about 30 apparent atomic layers of the metal, but this was reduced to about one-half this value when the surfaces were equilibrated for several days in inactive silver nitrate. Etched foils exchanged during one hour to a.depth of only about 2 apparent atomic layers and this was not affected by equilibration. Bowden-Rideal area measurements gave values of roughly 7 and 15 times the planar area for etched and abraded specimens respectively. These values were not altered by equilibration of the surfaces. Only about 50% of the acquired radioactivity was subsequently removable in inactive silver nitrate solution. Part of the measured radioactivity was present on the surface in adsorbed ionic form and was not removable by a simple water wash. The magnitude of this adsorbed activity was found to be measurable electrometrically.