The decomposition of hydrogen peroxide in aqueous solution proceeds very slowly. A bottle of
3% hydrogen peroxide sitting on a grocery store shelf is stable for a long period of time. The
decomposition takes place according to the reaction below.
2 H2O2(aq) → 2 H2O + O2(g)
A number of catalysts can be used to speed up this reaction, including potassium iodide,
manganese (IV) oxide, and the enzyme catalase. If you conduct the catalyzed decomposition of
hydrogen peroxide in a closed vessel, you will be able to determine the reaction rate as a function
of the pressure increase in the vessel that is caused by the production of oxygen gas. If you vary
the initial molar concentration of the H2O2 solution, the rate law for the reaction can also be
determined. Finally, by conducting the reaction at different temperatures, the activation energy,
Ea, can be calculated.
OBJECTIVES
In this experiment, you will
 Conduct the catalyzed decomposition of hydrogen peroxide under various conditions.
 Calculate the rate constant for the reaction.
 Determine the rate law expression for the reaction.
 Calculate the activation energy for the reaction.
Figure 1
MATERIALS
Vernier computer interface 3% hydrogen peroxide, H2O2, solution
computer 0.5 M potassium iodide, KI, solution
Vernier Gas Pressure Sensor 18  150 mm test tube
thermometer or Temperature Probe two 10 mL graduated cylinders
one-hole rubber stopper with stem graduated plastic Beral pipet
tubing with two Luer-lock connectors 1 liter beaker
solid rubber stopper (#1) ~800 mL room temperature water
distilled water