Genie in a Bottle

Purpose: The purpose of the Genie in a Bottle demonstration is to illustrate how a catalyst can rapidly speed up the rate of a reaction. The reaction used is the decomposition of hydrogen peroxide, which is normally slow, but is sped up significantly with certain catalysts.

2 H2O2 catalyst 2 H2O + O2

Equipment: 500 ml Erlenmeyer Flask and appropriate sized stopper (or 500 ml plastic bottle with lid), Ring Stand, 100 ml Graduated Cylinder, Aluminum Foil, String, Tissue Paper or Kim Wipe, Chemical Resistant Gloves, Goggles, and Shield

Chemicals: 30% Hydrogen Peroxide, the catalyst can be either Manganese Dioxide, Sodium Iodide, or Potassium Iodide, and Household 3% hydrogen peroxide bottle (may be empty).

Procedure:

This demonstration requires setup ahead of time. All of these steps except for step 10 must be carefully performed in advance.

  1. Using a clean flask or bottle tightly wrap it in aluminum foil. This is done so that students can’t see that a catalyst will be dangling inside.
  2. Measure out a small sample (~2 grams) of your catalyst and place it on a square of tissue paper. Fold the paper up to trap the catalyst inside and twist the paper into a tear drop. Tie your string around the paper so that it is firmly held.
  3. Tie a knot in the string around 1 to 2 inches from the paper a leave and little tail hanging past the knot. When fully assembled this knot will hold the paper up because the stopper will catch the knot. When the stopper is removed later the string and paper will fall into the hydrogen peroxide solution. However, at this point set aside your string and paper and make sure it does not get anywhere near the hydrogen peroxide.
  4. Put on goggles and gloves while measuring the hydrogen peroxide. See safety precaution regarding hydrogen peroxide. Measure 40 to 50 ml of H2O2 in your graduated cylinder and then add it to your flask or bottle. Pour it slowly and avoid letting the solution hit around the mouth of the flask.
  5. Preparing your lid/stopper. If you are using a stopper be sure it has holes in it. Many stopper have the option of 1, 2 or 3 holes. You want to pick one with three holes. If you are using a plastic bottle then you want to make a couple of holes in the cap. Why? Well the hydrogen peroxide will be decomposing inside even before the catalyst is added and you don’t want the pressure to build up. The other reason is safety related.
  6. Now you are going to suspend the catalyst in tear drop paper above the solution. Lower the catalyst in tear drop an inch or so into the flask or bottle. Hold the string so that the knot you tied earlier is just barely outside the container. Insert the stopper or screw on the cap firmly making sure that the string cannot slide at all.
  7. You have now fully assembled your Genie in a Bottle. Use extreme caution when moving it for your demonstration as you do NOT want the catalyst to get splashed and start the reaction unintentionally.
  8. Lastly, if you choose to use a plastic bottle you will want to place the bottle inside a ring so that it doesn’t accidentally fall over. Why would I ever want to use a plastic bottle? Well this reaction is extremely exothermic. So much heat is produced that the plastic bottle will shrink as it cools back down. This is a very unique way of demonstrating heats of reaction as well as discussing the concepts of Thermoplastics. If you choose to use an Erlenmeyer Flask you won’t need a ring stand as the glass won’t change shape and there is no danger of it falling over.
  9. Now it’s time for a demonstration. Be a showman but be safe. Think through what you want to say. This is a great demonstration to start a chemistry magic show with, so make up a story about releasing the magic of the genie etc…
  10. Place your flask on the front demonstration desk (or bottle in the ring stand). Say your little story about magic in a bottle, catalytic chemistry, or whatever way you have chosen to use this demonstration. Carefully remove the stopper or unscrew the lid. Back away several feet. If there are students within 8 to 10 feet you should either ask them to back away or you may use a blast shield. When you take the stopper off (or remove the lid) the catalyst will drop down into the hydrogen peroxide. In one to two seconds you will see a huge amount of steam produced and shooting out of the top very rapidly. This steam is incredibly hot.
  11. Afterward discuss the chemistry, catalyst, energy released, gas pressure, changes in volume from liquid to solid, and if you used a plastic bottle you can peel off the aluminum foil when it has cooled a show that the bottle shrank around 50% after it cooled back down. At this point you may also hold up a bottle of household hydrogen peroxide and point out it expiration date.

Here is a video link to watch so that you can see what should happen before trying it yourself.

Safety Precautions:

  1. 30% Hydrogen Peroxide is caustic and will burn your skin. Wear chemical resistant gloves when pouring hydrogen peroxide and ensure the cap is tightly applied when not in use.
  2. The reaction produces extremely hot steam and caution should be taken so that no one is burned by the steam. If using a plastic bottle place the bottle in the ring of a ring stand so that it cannot fall over during the demonstration.
  3. Do NOT seal the container tightly. If you are using a stopper be sure it has several holes in it.
  4. Once everything is assembled the bottle must be moved with the greatest caution so that the reaction does NOT take place unexpectedly. Meaning, do NOT shake or splash the hydrogen peroxide into the catalyst as the reaction can build up pressure drastically if the bottle or flask is sealed.
  5. If you spill hydrogen peroxide on yourself rinse impacted area immediately for 10 to 15 minutes. Spills on skin will result in minor burns, the skin may turn white and itch intensely. This is why it is recommended you wear gloves when preparing the demonstration and why you should wear them during the demonstration.
  6. If you spill in your eyes rinse them immediately in the eye wash for 15 minutes and seek medical attention. Spills in the eye can result in extreme damage to the eye and result in blindness. Proper goggles must be worn at all times.

Sources:

“Genie in a Bottle The Exciting Nature of Chemistry” Flinn Scientific Inc., Chem Fax Publication No. 92100.

Material Safety Data Sheet - Hydrogen Peroxide 30% MSDS