# A clock reaction is run at 20°C with several different mixtures of iodide, sodium bromate and...

## Question:

A clock reaction is run at 20°C with several different mixtures of iodide, sodium bromate and acid, to form iodine. Thiosulfate is used to react with the iodine formed initially. Starch indicator is added to form a blue color when all the thiosulfate has been used up and the iodine concentration begins to rise. Mixtures with the following initial concentrations are used:

Run number [I-] [BrO3-][H+]
10.0020.0080.02
20.0020.0160.02
30.0040.0080.02
40.0020.0080.04

[S2O32- ] is equal to 0.0001M in each reaction mixture. The rate law is Rate = {eq}k [I^-]^a[BrO_3^-]^b[H^+]^c {/eq}. The reaction time is 30 s in run 1, 30 s in run 2, 15 s in run 3, and 30 s in run 4. Calculate a, b, and c in the rate law.

## Clock Reaction:

A clock reaction is a chemical reaction that can be used as a clock, meaning that the reaction can be used to measure time. That is possible because the observable changes of the reaction happen after a period of time that can be predicted relatively easily.