[taydaniel]

Hi, anyone knows why is the iodine-persulfate reaction called the iodine clock reaction ?

[lemonoman]

Perhaps because it is one of the few reactions in solution which has a visible change occurring in a time measurable on any standard clock.

Most reactions in solution occur very quickly and almost instantaneously because they are directly related to ion/molecule mobility (relatively high in solution).  But because this reaction concerns a very slow in-solution reaction (the reaction of iodine with hydrogen peroxide)...the time of completion of the second reaction is much longer than 'instantaneous'...and can, for a fact, be measured on any clock.

If there's another reason that I'm missing, feel free to correct me