The Research Experience for Teachers Program /

Subject Area(s): Chemistry

Computer Science Tools: Windows Movie Maker, Spreadsheet software

Activity Title: “Timing the Iodine Clock Reaction”

Grade Level: 10-12

Time Required: 90 minutes

Recommended Group Size: 2-3 people

Summary: Students will discover the different methods available to alter the rate of a chemical reaction by performing trials on a reaction with a defined color change. To obtain the most accurate time measures, students will use Windows Movie Maker to determine the time duration of each reaction to a high degree of precision. Students will also use spreadsheet software to try to ascertain the relationship between concentration of reactants and the rate of the reaction, providing a very quick introduction into the concept of the rate law.

Educational Standards:

NC Chemistry Essential Standard: 3.1.1.: Explain the factors that affect the rate of a reaction (temperature, concentration, particle size, and presence of a catalyst).

Computer Science Connection: Students will use Windows Movie Maker as a means of accurately timing the rate of a reaction. They will also use spreadsheet software as a means of establishing relationships between two variables.

Keywords: Kinetics, catalyst, collision theory, activation energy

Materials List:

0.05 M KI3% H2O21% Starch solution1-mL syringe

0.10 M HClSolid KI24-well microplatesScoopula

0.01 M Na2S2O30.001 M CuSO45 50-mL beakers5 Disposable pipets

Hot plateTest tube tongsCrushed ice10 test tubes

ThermometerWeigh boatsMortar/pestleGraduated cylinders

Laboratory handout

Teacher Notes:

  • The handout provided contains two separate versions of the activity—an inquiry format and a guided activity format. Either option can be used. All protocols for each setup are contained in the handout.
  • The calibration activity can be done as a class to give the students an opportunity to “practice” the experimental setup before they actually break into groups to perform their trials. It can also be done by the instructor prior to class; the instructor can then just inform the students of the appropriate amount of sodium thiosulfate use.
  • When dividing students up, assign a specific set of conditions to be tested per group. For instance, one group may be assigned to perform the experiment with the hot water bath while another will perform the experiment in a cold water bath. Likewise, one group of students may perform the experiment with a catalyst present while another will run a control that does not utilize a catalyst.
  • Note that not all materials will be needed for every group. Groups not focused on temperature will not need ice or a hot water bath. Likewise, only the surface area groups will need a mortar and pestle.
  • For advanced groups, a challenge could be issued where students try to setup a reaction system that will produce a reaction that will require a specified amount of time. For example, students may be challenged to set up a reaction that will take twenty seconds to react.
  • If the experiment produces questionable results, particularly those in which it is hard to establish a pattern, the handout includes a sample set of data collected that can be used for discussion.

Reference(s)

Appalachian State University RET Program 2014,

“Carolina Investigations for AP Chemisty: Factors Affecting Reaction Rates”. Carolina Biological and Supply Company, 2012.