500-mL Pyrex Florence or Erlenmeyer flask (painted on outside)
1-hole rubber stopper to fit the flask
50-mL Hydrogen peroxide
rubber or plastic gloves
safety glasses
long stem glass funnel
facial tissue ( Kleenex )
white thread or string
1-teaspoon of manganese dioxide ( powdered, not granular )
SAFETY:
When using high strength hydrogen peroxide, use safety glasses and rubber gloves. It is very reactive and is a strong oxidizing agent. Wash your hands with water immediately on contact as it will blister and discolor your skin (white). Do NOT allow students to do the Demo. Clean up all glassware with copious amounts of water after completion of the Demo.
PREPARATION:
1. Using the long stem funnel, carefully add 50-mL of hydrogen peroxide to the bottom of the flask being very careful not to spill any on the neck of the flask.
2. Add 1-teaspoon of powdered manganese dioxide to a Kleenex tissue (1-ply only) and tie off the ball with the string. I recommend you trim any excess tissue with scissors.
3. Holding the thread, carefully lower the catalyst ball down the neck of the flask without dipping it into the solution. Stopper the flask with the 1-hole stopper to hold the string in place.
4. Do NOT use a solid rubber stopper. A hole is needed to properly vent the gases which are produced either by slow decomposition or premature contact with the catalyst. Avoid unnecessary movement of the bottle.
DOING THE DEMO:
You may want to tell some story about the Genie-in-the-Bottle or even create one yourself. Don't forget to say "The Magic Words" to make your genie appear. Stand off to the side of the flask, say the words, and carefully remove the stopper from the flask. This releases the ball of manganese dioxide catalyst into the liquid below. The "Genie" appears as a plume of white condensed water vapor as it rapidly emerges from the flask. The condensed water vapor that emerges ( what most people mistakenly call "steam" ) is extremely exothermic so be very careful. The flask also gets rather hot so please allow it to cool before picking it up.
THE SCIENCE:
Hydrogen peroxide typically decomposes to form water and oxygen at the rate of 10% per year even if capped sufficiently. What we are doing here is decomposing the liquid at a faster rate with the addition of a catalyst ( manganese dioxide ). The reaction can be accelerated by heat, light, or a catalyst. That is why we typically store hydrogen peroxide in a brown bottle in the refrigerator. A CATALYST we know is a compound that speeds up the rate of reaction without itself being consumed by the reaction. So when the manganese dioxide acting as the catalyst drops into the hydrogen peroxide, the faster rate of decomposition occurs. Steam ( which is a superheated form of water and is invisible ) escapes from the bottle and is very EXOTHERMIC. When this steam emerges it immediately condenses to the visible white plume of water vapor because of the temperature difference of the room ( the room is cooler ). The appearance of the "Genie" is caused by this cloud exiting from the flask. When I make an especially robust cloud, I tell them it is Burl Ives ... the smaller ones are Barbara Eden. Of course, they have no idea what I am talking about ! Enjoy !!!
