For this reaction S2O82-(aq) 3I-(aq)2SO42-(aq) I3-(aq), we can use spectrophotometer to decide the concentration due to___is colored

I3-(aq)

Explanation:

To measure the rate of this reaction we must measure the rate of concentration change of one of the reactants or products. This reaction may also be referred to as the iodine clock reaction. It yields the triodide ion which forms a blue complex with starch which enhances the determination of iodine even though iodine is coloured also.

Since the reaction is monitored by spectrophotometry, the concentration of the triodide ion can be monitored by spectrohotometric detection of the concentration of triodide ion present in the system. Hence we can use the determination of the amount of triodide ion by spectrophotometry to understudy this reaction.