Clock Reaction


Purpose:

  1. To observe how the rate of reaction varies with the addition of a catalyst.
  2. To observe how the rate of reaction varies with an increase of temperature.

Materials:

  1. .024M solution Potassium Iodate
  2. .016M solution Sodium Bisulfate w/ starch
  3. .01M CuSO4
  4. Dropper
  5. (6) thermometers
  6. (2) 20 mL graduated cylinders
  7. Stop watch w/ seconds hand
  8. Stirring rod
  9. (12) 50 mL beakers
  10. Hot Plate
  11. Ice

Procedure:

  1. Prepare 6 beakers with 20 mL of Solution A.
  2. Prepare 6 beakers with 20 mL of Solution B.
  3. Add 5 drops of catalyst to 5 of the 6 beakers of Solution A.
  4. Pair each beaker of Solution A with a beaker of Solution B.
  5. (UsingONLY the 5 beakers of Solution A with the catalyst (and their pairs)) Cool 2 samples of Solution A (and their pairs) with ice, and heat 2 samples of Solution A (and their pairs) as to create a result of one beaker (and its pair) in each of the different temperature ranges. (5-10 oC, 10-20 oC, 20-30 oC, 30-40 oC, 40-50 oC.)
  6. NOTE: The beaker with Solution A without the catalyst (and its pair) is to be kept at room temperature.
  7. Record the temperatures of each solution.
  8. Mix the paired solutions together, starting the stop watch at the moment that they are mixed. Record the time when the reactions change color.

Data & Information

Temp oC Start Time Stop Time Time Required (seconds)
sec sec sec sec
sec sec sec sec
sec sec sec sec
sec sec sec sec
sec sec sec sec
sec sec sec sec


Questions:

  1. What color did the solutions change?
  2. Describe the effect of temperature on the reaction rate.
  3. Describe the effect the catalyst has on the reaction rate.