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Instructions
Preparation
Fill a 400-ml beaker with distilled water to use for dilutions. You will prepare a number of different concentrations of solutions to explore the effect of concentration on the reaction.
Label two 400-ml beakers, two 10-ml graduated cylinders and two sets of five test tubes with an "A" or a "B" to indicate which solution they will be used with. If you use the same glassware for both solutions, you will risk contaminating the experiment. Label a 100-ml beaker with "Reaction" to indicate the reaction beaker.
Pour approximately 60 ml of iodate solution in the 400-ml beaker labeled "A" and 120 ml of bisulfite solution into the 400-ml beaker labeled "B." These will be the stock solution for your dilutions.
Place a pipet in each of the stock solution beakers for use in adding the final few drops to obtain a specific volume for a reaction run.
Experiments with Varying Concentration
Measure 1 ml of 0.02M iodate solution into the graduated cylinder labeled "A." Add distilled water up to the 10-ml mark.
Measure 10 ml of 0.002M bisulfite solution into the graduated cylinder labeled "B."
Add the contents of both graduated cylinders to the beaker labeled "Reaction" and start the stopwatch. Swirl the contents and place the beaker on a piece of white paper.
Watch the beaker for the appearance of the first bit of blue in the beaker. When you see the first signs of color, stop the stopwatch. Record the time and the amount of iodate solution and water used.
Repeat steps 1 to 4 with volumes of iodate at 3 ml, 5 ml, 7 ml and 10 ml. As the volume of iodate solution increases, the volume of added water will decrease. Clean the graduated cylinder A and the Reaction beaker thoroughly after each run to prevent carryover from the previous experiment.
Make a table for the results that shows the volume of iodate, volume of water and time to appearance of color. The time should increase with the increase in amount of iodate solution. The range of times should fall between 15 and 30 seconds.
Experiments with Varying Temperature
Place ice into a 400-ml beaker and add water to the ice until the beaker is half-full. This will generate an ice bath. Add hot water by the drop to adjust the temperature of the bath to 5 degrees C.
Place a thermometer in the ice bath and adjust the temperature of the ice bath to 5 degrees C.
Add 5 ml of iodate solution and 5 ml of distilled water into one of the test tubes. Add 10 ml of bisulfite solution to one of the other test tubes.
Place both test tubes and the reaction beaker into the 400-ml beaker containing the ice bath. This will help the reactant solutions and reaction beaker to equilibrate to 5 degrees C.
Wait about 15 minutes to make sure all the test tubes have reached the same temperature. Record the temperature of the ice bath.
Add the contents of both test tubes to the reaction beaker and swirl the solution to mix it well. Start the stopwatch at the same time you mix the solutions.
Observe the reaction beaker and stop the watch when you see the first signs of blue color. The appearance of blue indicates the reaction has reached completion.
Repeat the process using new test tubes and a clean reaction beaker for temperatures of the water bath at 10 degrees C, 20 degrees C, 28 degrees C and 35 degrees C. Adjust the water bath temperature, allow the solutions to equilibrate and then record the time required for the solution to show the first signs of blue. The reaction times should fall between 10 and 30 seconds.