Hey guys. Any chemistry experts around? I just did Persulfate variation of the iodine clock experiment. http://en.wikipedia.org/wiki/Iodine_clock_reaction According to collision theory explained on this page, molecules need to hit each other in certain positions to react. Which molecule needs to hit which and in what direction in the iodine clock reaction? 2I−(aq) + S2O82−(aq) → I2 (aq) + 2SO42−(aq) and I2 (aq) + 2S2O32−(aq) → 2I−(aq) + S4O62−(aq) Thanks guys!