Decomposition of Hydrogen Peroxide

The decomposition of hydrogen peroxide in aqueous solution happens very slowly.

A catalyst can be used to speed up this reaction.Objectives:Conduct a catalyzed decomposition of hydrogen

peroxide.Calculate the rate constant k for this reaction.Determine the rate law for this reaction.Calculate the activation energy for this reaction.

Background

Materials Lab quest NetbookGas pressure sensorTemperature probe4 test tubes and test tube holderWash bottle/Distilled water3 % hydrogen peroxide (0.88M)100 mL volumetric flaskSolid potassium iodide2 10 mL graduated cylinders plastic pipettes 600 mL beakerRing stand and clampGlass pipette and pipette bulb

Procedure We will be doing 4 experiments during this

lab to determine the rate law of this reaction and the activation energy.

Solution Preparation We will be using store bought 3%(0.88M)

H2O2

We will need to make 100 mL of a 0.5 M KI solution.

How many grams of KI will we need? (molar mass of KI = 166.01 g/mol)

8.3 gIn experiment 2 we will be cutting the

concentration of our KI in half.In experiment 3 we will be cutting the

concentration of our H2O2 in half

Data TableExperimen

tReactants Temp (oC) Rate

(kPa/s)

1 4 mL 0.88 M H2O2 + 1 mL

0.50 M KI

2 4 mL 0.88 M H2O2 + 1 mL

0.25 KI

3 4 mL 0.44 M H2O2 + 1 mL of

0.50 M KI

4 4 mL 0.88 M H2O2 + 1 mL 0.50c M KI

Data AnalysisExperiment [H2O2] After

Mixing (M)[KI] After

Mixing (M)Rate (M/s)

1

2

3

4

Analysis Questions1. Using your data determine the rate law for

this reaction, and calculate the average value of k for the 3 experiments.

2. Determine the average numerical value of k for experiments.

3. The rate law should have been first order in both KI and H2O2 using this information determine the units for k.