A Closer Examination of the Mechanism of the Hydrogen Peroxide Iodine-Clock Reaction with Respect to the Role of Hypoiodite Species

Abstract

One step of the published mechanism of the hydrogen peroxide iodine-clock reaction is called into question by the result of an experimental attempt (predicated on that mechanism) to integrate that reaction into the elephant’s toothpaste demonstration to reveal and control its iodine side product. Under conditions that were a hybrid of those demonstrations (starch and thiosulfate added to the elephant’s toothpaste demonstration), there was a pronounced induction period preceding the appearance of both iodine and oxygen. This induction period for both of these products indicated that the reductant reacted not with iodine but with the transient intermediate, hypoiodous acid (or hypoiodite), common to both iodine and oxygen generation. Additional experiments based on the reaction of thiosulfate with 8 times more moles of hypoiodite than moles of iodine supported this conclusion.