The genie in a bottle chemistry demonstration is an exciting reaction often performed as a science magic trick. The person doing the demonstration commands a genie to appear from a bottle, which produces a dramatic cloud of steam. The genie in a bottle demonstrates a decomposition reaction, catalysis, a chemical change, and an exothermic reaction. It’s particularly appropriate accompanying the elephant toothpaste reaction, which works on the same principle and uses some of the same chemicals.
The basis for the genie in the bottle reaction is the decomposition of hydrogen peroxide. But, you need a more concentrated solution that household peroxide. Get the 30% peroxide solution from a beauty supply store, online, or a chemical supply company.
- 30 to 50 milliliter 30% hydrogen peroxide (H2O2)
- 1/4 teaspoon (about 0.5 grams) manganese dioxide (MnO2)
Popular glassware choices include a colorful wine bottle or 1-liter volumetric, Florence, or Erlenmeyer flask. You can substitute sodium iodide (NaI) for the manganese dioxide, although the effect won’t be as dramatic. Both chemicals are available online from chemical suppliers.
Perform the Genie in a Bottle Chemistry Demonstration
In a nutshell, all you do is pour the peroxide into the bottle and add the manganese dioxide or sodium iodide. With a little preparation, you can easily improve the dramatic effect.
- Pour the manganese dioxide or sodium iodide onto a piece of tissue paper or toilet paper.
- Wrap the paper around the chemical and make a little packet. Tie it closed using a bit of string.
- Pour 30 to 50 milliliters of 30% hydrogen peroxide into the bottle.
- Dangle the packet into the bottle, but keep it from contact with the peroxide by holding the string with a stopper. Make sure the stopper is loose, just in case the packet drops. You don’t want pressure to build up and break the glassware.
- When you’re ready, uncap the bottle. If you like, command the genie to appear. Maybe it will grant you three wishes! Probably not, but at least you’ll get a nice cloud of vapor.
How the Genie in a Bottle Works
Hydrogen peroxide has a shelf life because it slowly decomposes into water and oxygen:
H2O2 (aq) → 2H2O (l) + O2 (g) + heat
While this is an exothermic reaction, a stored bottle of peroxide does not feel hot because the rate of the reaction is very slow. A catalyst greatly speeds up the reaction. In this reaction, the catalyst is either manganese dioxide or else sodium iodide. Similarly, the elephant toothpaste reaction uses either potassium iodide, sodium iodide, or else catalase from yeast.
Uncapping the bottle releases the string and drops the packet of catalyst into the hydrogen peroxide. The catalyzed reaction releases so much heat that it boils the water that is present in the hydrogen peroxide solution and released by its decomposition. The narrow bottle opening directs the steam so it exits the bottle as a visible cloud.
Manganese dioxide is a heterogeneous catalyst. What this means is that the phase of the catalyst is different from the phase of the reaction. The solid manganese dioxide surface makes the decomposition reaction favorable, although the exact mechanism of action is not well understood. The size of the catalyst particles influence the rate of the reaction. So, you’ll get a different effect using a fine powder compared with granules. One advantage of the genie in a bottle reaction over the elephant toothpaste reaction is that you can recover the catalyst following the reaction and prove to students that it isn’t used up.
Safety and Clean-Up
- Wear proper lab safety gear, including goggles and gloves.
- Ideally, use a borosilicate flask or bottle. But, most glass bottles work fine. If you use a plastic bottle, expect warping and shrinking from the heat of the reaction.
- Do not point the bottle toward a person or pet. Similarly, because the bottle may become hot, don’t hold it while performing the reaction.
- Read the product labels for chemical safety information. In particular, note that hydrogen peroxide is a strong oxidizing agent and manganese(IV) dioxide is toxic. Unlike the 3% hydrogen peroxide commonly found in homes, it is not safe to touch. Do not sniff or drink the contents of the bottle.
- Dilute the bottle contents with water. You can filter out the manganese dioxide, dry it, and re-use it. Wash the liquid down the drain. Dilute any spills with plenty of water before clean-up.
- Dirren, Glen; Gilbert, George; Juergens, Frederick; Page, Philip; Ramette, Richard; Schreiner, Rodney; Scott, Earle; Testen, May; Williams, Lloyd (1983). “Chemical Demonstrations.” A Handbook for Teachers of Chemistry. 1: 180–185. doi:10.1021/ed062pA31.2
- IUPAC (1997). “Chemical decomposition.” Compendium of Chemical Terminology (2nd ed.) (the “Gold Book”). Oxford: Blackwell Scientific Publications. ISBN 0-9678550-9-8. doi:10.1351/goldbook
- Kauffman, George B.; Shakhashiri, Bassam Z. (2013). “Chemical Demonstrations: a Handbook for Teachers of Chemistry, Volume 5.” Foundations of Chemistry. 15(1): 119-120. doi:10.1007/s10698-011-9137-6