Chemistry: Kinetics of the Iodine Clock Reaction

Research Question: What will the effect of a change in temperature have on the rate of reaction of hydrogen peroxide with iodide and hydrogen ions.

Independent Variable: Changing the Temperature of the reaction.
Dependent Variable: The rate of reaction.
Control: The concentration of the reactants.

Hypothesis: An increase in temperature will increase the rate of reaction. “For many reactions happening at around room temperature, the rate of reaction doubles for every 10°C rise in temperature.” (chemguide.co.uk) We should see a faster reaction time take place every time our temperature is raised.

Procedure: For the hypothesis to be proven or disproven, the lab would have to be repeated several times. To start out, make four water baths: one at 5°C, one at 10°C, one at 15°C and one at 20°C. This will prove whether an increase in 10C actually doubles the rate of reaction or if a smaller increase in temperature would have the same effect. Achieve this by using a kettle for hot water and ice to cool water down. Keep a thermometer in each water bath to keep the temperature constant for the duration of the reaction. Next, place a test tube containing a mixture of hydrogen peroxide and iodine ions into the water bath without allowing water to enter. Using a stopwatch, time the reaction process and record observations. Repeat for each temperature.

Temperature (°C) | 5°C | 10°C | 15°C | 20°C | Time for Reaction