Iodine atoms will combine to form in liquid hexane solvent with a rate constant of . The reaction is second order in .

Iodine atoms will combine to form in liquid hexane solvent with a rate constant of . The reaction is second order in . Since the reaction occurs so quickly, the only way to study the reaction is to create iodine atoms almost instantaneously, usually by photochemical decomposition of . Suppose a flash of light creates an initial concentration of 1.50×10−2 .