The iodine clock reaction (also known as the Harcourt-Esson reaction or the Harcourt-Essen reaction) is a classical chemical clock demonstration experiment to display 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 time delay, the liquid suddenly turns to a shade of dark blue. The iodine clock reaction exists in several variations. In some variations, the solution will repeatedly cycle from colorless to blue and back to colorless, until the reagents are depleted.
Read more about Iodine Clock Reaction: Hydrogen Peroxide Variation, Iodate Variation, Persulfate Variation, Chlorate Variation
Famous quotes containing the words iodine, clock and/or reaction:
“During Prohibition days, when South Carolina was actively advertising the iodine content of its vegetables, the Hell Hole brand of ‘liquid corn’ was notorious with its waggish slogan: ‘Not a Goiter in a Gallon.’”
—Administration in the State of Sout, U.S. public relief program (1935-1943)
“The clock runs down
timeless and still.
The days and nights turn hours to years
and water in a gutter marks the circle of another world
hating, resentful, and afraid
stagnant, and green, and full of slimy things.”
—Margaret Abigail Walker (b. 1915)
“The excessive increase of anything often causes a reaction in the opposite direction.”
—Plato (c. 427–347 B.C.)