Abstract
The kinetics of active iron dissolution at 25°C has been studied in deaerated 1N and 6N chloride solutions for hydrogen ion concentrations of 0.1–6.0N. For 1N chloride solutions with 
, the dissolution reaction is described by anodic Tafel slope 
and electrochemical reaction order with respect to hydrogen ion activity 
. These parameters are characteristic of a dissolution mechanism in which chemisorbed halide ions interact with adsorbed hydroxyl ions in a two‐electron rate‐determining step. For 6N chloride solutions, this mechanism holds only over a narrower (H+) region up to 0.24N, in which 
. With increased 
; and for 
, indicating that the hydrogen ion (and no longer the hydroxyl ion) catalyzed the dissolution reaction. A positive value of 
ensues for synergistic adsorption of hydrogen ions on the halide ion covered surface. A formal detailed dissolution mechanism is proposed, giving 
and 
, in agreement with experiment. Alternate dissolution mechanisms including one‐electron transfer schemes are discussed.