Chlorate Variation
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:
- I3− → I− + I2
Chlorate ion oxidizes iodide ion to hypoiodous acid and chlorous acid in slow and rate-determining step:
- ClO3− + I− + 2 H+ → HOI + HClO2
Chlorate consumption is accelerated by reaction of hypoiodous acid to iodous acid and more chlorous acid:
- ClO3− + HOI + H+ → HIO2 + HClO2
More autocatalysis when newly generated iodous acid also converts chlorate in the fastest reaction step:
- ClO3− + HIO2 → IO3− + HClO2
In this clock the induction period is the time it takes for autocatalytic process to start after which the concentration of free iodine falls rapidly as observed by UV/VIS spectroscopy.
Read more about this topic: Iodine Clock Reaction