The Iodine Clock Reaction
The Iodine Clock Reaction
The iodine clock reaction (also known as the Harcourt–Esson reaction) is a classic chemical clock experiment for displaying chemical kinetics in action; it was discovered by Hans Heinrich Landolt in 1886. Two colorless solutions are mixed and at first there is no visible reaction. After a short, predictable time delay, the liquid suddenly turns a shade of dark blue.
Adjustment of the relative amounts of the iodate and the bisulfite determines the time interval (shown on the graph) before the blue color appears.