A study of Liesegang band formation is presented with emphasis on the dependence of the precipitation pattern on its solubility. The formation of Cr(OH)3 precipitate has been studied by diffusing NaOH into chemically cross-linked poly(vinyl alcohol) gel containing Cr(NO3)3. The precipitate can sparingly redissolve in the surplus of NaOH. The formation, together with the dissolution of the precipitate, coupled with diffusion leads to a propagating band, instead of a final static pattern. A crossover from traveling band to Liesegang pattern formation has been also observed. A model, based on reaction-diffusion phenomenon, allows us to correlate the band movement with various kinetic and chemical processes.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry