Unformatted text preview: “time”; set the frequency to 2 Hz for automated data
There are two solutions available; the iodate solution, and the sulfite solution.
You will want to get a sample of each in individual clean, dry containers. You will also
want distilled water to be available. If the concentrations are given, record them;
however, the concentrations may not be given (this is not a problem).
In a small test tube, put about 1 mL of the iodate solution. Quickly put 1 mL of
the sulfite solution, and allow the solution to stand. Wait for a reaction to occur. Take
observations; this is so you can see the reaction once before using the Pasco equipment.
Measure out two millileters of iodate solution and put it into a cuvette. Place the
cuvette into the colorimeter. One partner should be ready to press “record”, while the Dakota State University page 187 of 232 Experiment 18: Kinetics General Chemistry I and II Lab Manual other pours the solution. When you are ready, one partner should pour two millileters of
the sulfite solution into the cuvette and quickly close the colorimeter cover, while the
other partner starts recording the data. You are waiting for absorbance to rapidly
increase; it should level off shortly thereafter.
Clean and dry the cuvette and test tubes. In one test tube, place one milliliter of
iodate solution, and one millileter of distilled water. In the other, place two millileters of
sulfite solution. Repeat the above procedure for using the colorimeter to collect data.
For the third trial, after cleaning and drying the cuvette and test tubes, place two
millileters of iodate solution into one test tube, and one millileter of sulfite, plus one
millileter of water in the other. Again, run the reaction to collect data.
From the graphs, determine the rate of reaction for each of the three runs in
seconds. Notice that between run two and run one, we doubled the concentration of
iodate while keeping the concentration of sulfite constant. From the data, determine the
value of x. In an analogous manner, determine the value of y from runs one and three.
Choose one of the runs, and determine your experimental value of k. Dakota State University page 188 of 232 Experiment 18: Kinetics General Chemistry I and II Lab Manual Observations:
Reaction observations: Run
3 [Iodate] [Sulfite] Rate=1/time (sec) Observations: Dakota State University page 189 of 232 Experiment 18: Kinetics General Chemistry I and II Lab Manual Pre-Lab Questions:
1. How are we varying the concentrations of the reactants?
2. At one point, I mentioned that the exact concentratio n of the reactants is not
important. Is this true? Why or why not? Dakota State University page 190 of 232 Experiment 18: Kinetics General Chemistry I and II Lab Manual Post-Lab Questions:
1. What did you find for the overall order of the reaction?
2. List possible sources of error; how could this experiment be improved?
3. You were asked to perform the reaction outside of the colorimeter once before
collecting data. Consider the graphs that you obtained. Do these graphs make intuitive
sense based on this first re...
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