This experiment is designed to study the kinetics of a chemical reaction. The reaction involves the oxidation of iodide ions by bromate ioons in the presence of acid.
6I- (aq) + BrO3- +6H+ (aq)--> 3I2 (aq) + Br-(aq) +3H2O (l)
To find the rate of reaction, a method is needed to measure the rate at which one of the reactants is used up, or the rate at which one of products is formed. IN this experiment, the reate of reaction will be measured based on the rate at which iodine forms. The reaction will be carried out in the presence of thiosulfate ions, which will react with iodine as it forms:
I2 (aq) + 2S2O32-(aq) ---> 2I- (aq) + S4O62-(aq)
While the first reaction is somewhat slow, the reaction of iodine with thiosulfate is quite rapid, so that as quickly as the I2 is produced in the first reaction, it is consumed in the second reaction. I2 will continue to be conusmed until all the thiosulfate is used up. At that poin the accumulating I2 will form a deep blue colored complex with the starch. We will keep the concentration of thiosulfate constant in this experiment. Stochometry will permit us to relate the moles of S2)32- to moles of I2 and ultimately moles of BrO3-. We will define rate as -delta[BrO3-]/delta t
This is only the average rate, as rate changes continuously throughout the reaction. However, we are using concentrations that are designed to remain relatively constant throughout the reaction. As a result, the average rate should be close in value to the instantaneous rate.
This experiment will be done in microscale, meaning the you will be measuring volumes not in milliters but in drops. This has the advantage of allowing you to complete many trials quickly with very little waster produced. However, since the total solution volume is quite smal, even one extra drop can cause a substantial change in concentrations, so be careful.
Procedure:
1.) Use distilled water dropper to find the volume a drop. The average of one drop was .03316 mL
2.)You must design an experiment that will give you sueful concentration and rate data. Consider the following guidelines:
1.) Always use 1 drop each of starch and Na2S2O3.
2.) Always use 12 drops total.
3.) Always add the KBrO3 last and start the timer after you add those drops
4.) The starting concentrations are as follows:
[KI]= 0.010
[HCl]= 0.10
[Na2S2O3]= 0.0010
[KBrO3]= 0.040 M
This is my data: 1 drop=.03316 mL
How do I find the reaction rate and concentrations of each reagent?
How do I find K?
Using initial rateese is only one way of determing the reate law. Another more common method measures the concentration of a reactant or product as a function of time. Descrivve the steps that would be necessary to determine the rate law if this other method were used.

Trial [I-][BrO3-][H+]Time
13 (drops) 222:11.11
26221:11:56
33421:01.81
432422.15
53221:29.07
66221:04.50
734230.57
832425.31
93221:38.03
1062248.94
1134248.50
1232423.50
133221:37.84
1462231.00
1534246.47
1632425.65
173221:21.59
1862235.40
1934252.34
2032421.72
213221:22.81
2262238.97
2334251.34
2432422.25
2532296.74
2662248.23
2734252.17
2832423.43
Average of trials:
Trial [I-][BrO3-][H+]Time
132286.74
262248.23
334252.17
432423.43