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

Abstract

During electrolysis of an acid chloride solution, atomic chlorine is taken up by a graphite anode. After switching off the current the evolution of molecular chlorine continues. This phenomenon we call residual gas evolution (r.g.e.) It is established that the molecular chlorine is formed according to the Volmer-Heyrovsky mechanism, ▪ The rate of r.g.e. is determined by an equilibrium between the diffusion of atomic chlorine out of the graphite and the formation of molecular chlorine. During the first seconds it is the latter that mainly determines the rate of r.g.e.; thereafter the diffusion becomes more and more the rate-determining step.