Electrolysis of an acidic NaCl solution with a graphite anode : IV. Chlorine evolution at a graphite electrode after switching off current

During electrolysis of an acid chloride soln., at. Cl is taken up by a graphite anode. After switching off the current, the evolution of mol. Cl continues. This phenomenon is designated as residual gas evolution (RGE). The mol. Cl is formed according to the Volmer-Heyrovsky mechanism, Clads + e -> Cl- and Cl- + Clads -> Cl2 + e. The rate of RGE is detd. by an equil. between the diffusion of at. Cl out of the graphite and the formation of mol. Cl. During the 1st sec, it is the latter that mainly det. the rate RGE; thereafter the diffusion becomes more and more the rate-detg. step. [on SciFinder (R)