As a high school science teacher, I love to do demonstrations that have an element of magic but can be explained by science. This demo is a perfect combination of science and magic - the Genie in a Bottle Trick.
Supplies for the Genie in a Bottle Trick
Manganese dioxide powder
Hydrogen peroxide (I use 30% from a science supply company, Amazon only ships 12% or less for safety reasons and will work for this experiment)
Flat Bottom Boiling Flask (I like a 1000 ml flask or larger)
Rubber Stopper (this will depend on the size of your flask)
Gold Paint (optional)
How to perform the Genie in a Bottle Trick
Measure about 4 grams manganese dioxide into a dry lens wipe or a small piece of coffee filter.
Wrap a string around the paper to hold the manganese dioxide inside and leave a long piece of string attached.
Add about 100 ml of 30% hydrogen peroxide to the flask. You can add more or less depending on the size of your flask or how much "smoke" you want to produce.
Lower the manganese dioxide "bag" into the mouth of the flask and leave the long string out of the top - DO NOT let the bag touch the hydrogen peroxide.
Use a rubber stopper to close the top and hold the string in place. DO NOT leave it unattended. If the bag were to touch the liquid, it will react violently and either shoot the cork our of the bottle or the bottle could explode.
The Genie: open the rubber stopper. The bag will fall into the liquid and will catalyze the decomposition reaction and steam and oxygen gas will shoot out of the opening!
The Science of the Genie in a Bottle Trick
Hydrogen Peroxide (H2O2) naturally breaks down into oxygen (O2) and Water (H2O) all on its own. But, this decomposition is very slow. On average, a bottle of hydrogen peroxide will lose about 2% of the H2O2 concentration per year.
Hydrogen peroxide under standard conditions is a liquid and as it decomposes, the oxygen that forms acts as a gas and the water acts as a liquid. Gases take up more space than liquids because the molecules are moving around more quickly. Likewise, this reaction is exothermic which means that heat is released as H2O2 decomposes. But, because the reaction is slow slow we may not notice the amount of heat produced and we may not notice the gas pressure building up in our bottle of hydrogen peroxide.
If we add a catalyst to this reaction, it can speed up the rate of decomposition drastically. The manganese dioxide does just that. It speeds up the reaction so that just about all of the H2O2 turns into water and oxygen gas very quickly. This causes the temperature to rise very quickly and the oxygen gas to move around very quickly which builds pressure and causes steam and oxygen gas to shoot out of the top of our flask - this is our "genie"!
This is the same reaction that is used in the classic Elephant Toothpaste Experiment but instead of using manganese dioxide, I use potassium iodide as a catalyst. Why do I use different catalysts? I find that the manganese dioxide more quickly dissipates into the liquid from the lens wipe "bag" than potassium iodide but either will work.
Hydrogen peroxide reaction balanced chemical equation
2H2O2(l) → 2H2O(l) + O2(g)
Keep on Learning! Craig Beals
**Warning: 12% and 30% hydrogen peroxide is very harmful. This experiment should not be performed by children and protective gloves, apron, and googles should be worn at all times**