An experimental iodine clock sequence has also been established for a system consisting of iodine potassium-iodide, sodium chlorate and perchloric acid that takes place through the following reactions.
Triiodide is present in equilibrium with iodide anion and molecular iodine:
Chlorate ion oxidizes iodide ion to hypoiodous acid and chlorous acid in the slow and rate-determining step:
Chlorate consumption is accelerated by reaction of hypoiodous acid to iodous acid and more chlorous acid:
More autocatalysis when newly generated iodous acid also converts chlorate in the fastest reaction step:
In this clock the induction period is the time it takes for the autocatalytic process to start after which the concentration of free iodine falls rapidly as observed by UV–visible spectroscopy.