Catalytic Decomposition of Hydrogen Peroxide
Hydrogen peroxide (H2O2) naturally decomposes to produce oxygen and
water. However, this process takes a very long time. It may be sped up by the addition of a
catalyst. In this experiment, we will use the iodide ion (I-) present in potassium iodide
or sodium iodide as a catalyst to speed up the decomposition of hydrogen peroxide. The reaction
is also exothermic, meaning that it releases heat.
The catalyzed reactions are shown below:
H2O2 (aq) + I-(aq) --> H2O(l) + IO-(aq)
IO-(aq) + H2O2 (aq) --> H2O(l) + O2 (g)
The overall reaction is as follows:
2 H2O2 (aq) --> 2 H2O(l) + O2 (g)
- 30% Hydrogen Peroxide (H2O2)
- Potassium iodide or Sodium iodide
- Food Coloring
- Liquid dish detergent (Palmolive)
- 1 Liter Graduated Cylinder
- A large basin or tarp to facilitate cleanup
- glowing splint (optional)
- Place the 1 Liter graduated cylinder in the center of the large basin or tarp.
- Pour 50 mL of 30% hydrogen peroxide into the graduated cylinder. Add two to four drops of
food coloring. Add a small layer of liquid dish detergent to the mixture.
- Prepare a saturated solution of potassium iodide or sodium iodide by adding an excess of
salt to deionized water. The supernate of these solutions is used to carry out the reaction.
- Swirl the contents of the cylinder and quickly add 5 mL of saturated potassium iodide
solution before the agitation has subsided. This reaction occurs rapidly, so stand back
immediately after adding the potassium or sodium iodide solution.
- The reaction produces water and oxygen gas. The oxygen gas is trapped in the foam bubbles
of the soap solution. To test for the presence of oxygen, you can introduce a glowing splint to
the graduated cylinder.
This experiment utilizes 30% hydrogen peroxide, which is a strong oxidizing agent (household
hydrogen peroxide is typically about 3%). Concentrated hydrogen peroxide can cause burns.
Wear latex gloves, safety glasses, and avoid contact with the skin and mucous membranes.
A safer version of this demonstration that utilizes 3% (household) hydrogen peroxide instead of
30% hyrogen peroxide is also available. See reference #2 below.
Disposal of Waste Products
All waste products may be safely disposed of down the drain upon addition of plenty of water.
- Conklin, A.R.; Kessinger, A. Demonstration
of the catalytic decomposition of hydrogen peroxide. J. Chem. Educ.,
1996, 73(9), 838.
- Trujillo, C.A. A
modified demonstration of the catalytic decomposition of hydrogen peroxide. J. Chem. Educ.,
2005, 82(6), 855.