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Demonstrations › Chemical Kinetics › 14.3A

Lecture Demonstrations

Chemical Kinetics

14.3A Catalytic Decomposition of H2O2  II - “Aladdin’s lamp”

Subjects: Kinetics, catalysis, exothermic reactions

Description: When a stopper is removed from a bottle, a large cloud of vapor and heat escapes giving the appearance of a jinni in a bottle.

Materials:

  • 1L Florence flask and a stopper to fit opening
  • Aluminum foil to cover bottle (optional)
  • 30-50 mL 30% H2O2‡
  • ~1/4 tsp solid KI or NaI‡
  • Kimwipe or tissue and string (optional)
  • ring stand, support ring, and clamp (optional)*

‡H2O2 is located in the refrigerator. KI and NaI are located in the chemical storage cabinet.
*Shared item: Locate on the shelf above the center bench.

Pre-Class Preparation:

1. For a more dramatic effect, cover the bottle with aluminum foil (optional)
2. Fill the Kimwipe with the KI or NaI and tie with a string (optional)
3. Place the H2O2 in the bottle.
4. Hang the KI or NaI inside the flask by securing the string against the mouth of the flask with the rubber stopper.

Procedure:

1. When ready to perform the demo, remove the stopper to let the KI or NaI fall into the H2O2. If you don’t want to use the Kimwipe, add solid KI or NaI via a spatula.
2. Hold the bottle by the neck and point the bottle up and in a safe direction.
Within a few seconds, an exothermic reaction will take place, producing a cloud of O2 gas and water vapor.
3. If you don’t want to hold the bottle, support it with a ring stand and clamp. 

Discussion:

The decomposition of H2O2 to O2 and water occurs on its own. The rate of the reaction can be substantially increased with the addition of a catalyst. Several substances, including potassium iodide and manganese dioxide are known to catalyze the reaction.

Overall Reaction: 2H2O2(aq) –> 2H2O(l) + O2(g) + heat

Using iodide, IO- is believed to be the reaction intermediate:

H2O2(aq) + I-(aq) –> H2O(l) + OI-(aq)

H2O2(aq) + OI-(aq) –> H2O(g) + O2(g) + I-(aq)

Safety:

Concentrated H2O2 can cause burns. Be sure to wear safety glasses and gloves when performing the experiment.

Disposal:

The waste products can be flushed down the drain with water.

References:

1. L. Summerlin, J. Ealy,  C. Borgford; Chemical Demonstrations: A Sourcbook for Teachers; Volume 2; p. 42-43; 1987
2. NCSU Department of chemistry lecture demonstration website: http://www.ncsu.edu/project/chemistrydemos/DemoList.html

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