Abstract
[Display omitted]
•The dynamics of propagation of a silver hydroxide precipitate band in pseudo-1D experiments show a power law behavior characteristic of diffusion-limited phenomena.•The width of the band increases with time, a behavior uncommon in precipitate band propagation.•The mechanism of propagation is based on the precipitation of AgOH followed by its conversion to Ag2O.•The method was successful in isolating the silver hydroxide precipitate.
When sodium hydroxide diffuses in a gel medium containing silver nitrate, silver hydroxide precipitates and forms a white band in a narrow glass tube. The silver hydroxide precipitate changes to brown silver oxide due to its instability in excess diffusing electrolyte. As a result, and in contrast to the Liesegang ring phenomenon, in which a series of bands forms, the whole AgOH band propagatesvia formation due toprecipitationand disappearance due to conversion to the more thermodynamic stable Ag2O. The dynamics of the propagating silver hydroxide band exhibits a power law behavior for the distance traveled and the velocity with time. The effect of changing the gelatin percentage on the occurrence and the width of the band were investigated and showed a linearly increasing width as a function of gel percentage until a specific gel percentage. The dependence of the formation of the precipitates on the local concentration of NaOH confirms that the mechanism of the AgOH band formation is diffusion regulated.