Dancing Gummy Bear Chemistry Demonstration

This entry was posted on by (updated on )
Dancing Gummy Bear Chemistry Demonstration
The dancing gummy bear chemistry demonstration is the rapid combustion of sugar. The flames are violet because of the potassium emission spectrum.

The dancing gummy bear chemistry demonstration is among the most memorable chemical reactions. The gummy bear candy “dances” amidst violet flames, smoke, and sparks. The reaction is highly exothermic and also illustrates oxidation, combustion, and a product-favored reaction. It is an impressive display of the energy contained in the sugar of a single candy. You only need a couple of chemicals and performing the demonstration is simple.

Materials

You need just two chemicals, a large glass test tube, and a heat source (unless you use sulfuric acid to initiate the reaction):

  • Gummy bear candy
  • Potassium chlorate [make it yourself]
  • Large glass test tube (diameter larger than the candy)
  • Ring stand
  • Bunsen burner or other heat source
  • Long-handled tongs

Perform the Dancing Gummy Bear Chemistry Demonstration

The procedure is easy!

  • Place a small scoop of potassium chlorate in the test tube. The exact amount is not important, but aim for the same mass or less as that of the candy.
  • Using the ring stand, set up the test tube and place it over the heat source. You want the tube to tilt at a slight angle away from vertical to minimize the risk of the reaction propelling the gummy bear outside of the tube.
  • Heat the potassium chlorate until it melts.
  • Using long-handled tongs, drop a gummy bear into the test tube and stand back.

Substitutions and Alternate Procedures

  • Use sodium chlorate instead of potassium chlorate. With sodium, the flames are yellow to orange. Otherwise, the procedure is the same.
  • Substitute a different candy or a sugar cube for the gummy bear.
  • Place the gummy bear candy on top of cold potassium chlorate. When you’re ready to start the reaction, add a couple of drops of sulfuric acid to the contents of the test tube. This is essentially the instant fire demonstration, since it requires no heat source. Use either a watch glass or a large test tube.

The Chemistry of Dancing Gummy Bears

Ultimately, the dancing gummy bear demonstration is the very rapid combustion of sugar (sucrose, C12H22O11). The reason the reaction is so vigorous is because the potassium chlorate (KClO3) decomposes into potassium chloride (KCl) and oxygen (O2) and acts as an oxidizer.

2KClO3(l) → 2KCl(s) + 3O2(g)

C12H22O11(s) + 12O2(g) → 12CO2(g) + 11H2O(l) + heat ∆rH° = -5645 kJ/mol-rxn

The overall reaction is:

6KClO3 (l) + C12H22O11 (s) → 12CO2 (g) + 11H2O (g) + 6KCl (s)

The oxidizing power of potassium chlorate lends it to practical applications, such as safety matches, fireworks, propellants. It is a source of oxygen gas in the laboratory or for use as a disinfectant or herbicide.

The reason the flame is violet is because of the emission spectrum of potassium, which is its characteristic color in the flame test in chemistry. The combustion of sugar smells of burning candy and also gives off a lot of smoke. The residue remaining in the glass consists mainly of carbon and potassium chloride.

Safety and Disposal Information

  • After the demonstration ends, let everything cool to room temperature before clean-up. Washing the cooled chemicals down the drain with water is fine. But, you probably want to soak the glassware overnight in water for easier cleaning.
  • This project involves fire and should only be performed by responsible adults.
  • Only perform the dancing gummy bear demonstration in a well-ventilated area, ideally within a fume hood.
  • Wear safety goggles and gloves, tie back long hair, and employ the usual lab safety protocols.
  • Because the chemical reaction is vigorous and exothermic, there is a strong possibility of it shattering the glass. Minimize the possibility by using borosilicate glass (Pyrex or Kimax) that has an internal diameter larger than the candy and using the minimum amount of potassium chlorate and candy. Perform the demonstration a good distance from the audience, ideally behind a safety screen. Placing a cookie sheet or other metal pan beneath the reaction collects potential breakage and contains flames.
  • Do not store candy (or any sugar) with potassium chlorate. Potassium chlorate is such a strong oxidizer that the reaction may initiate on its own.
  • Store potassium chlorate away from flames. Use care removing it from the container (i.e., don’t generate sparks by roughly scraping it with a metal spatula).

References

  • Cotton, F. Albert; Wilkinson, Geoffrey (1988). Advanced Inorganic Chemistry (5th ed.). New York: John Wiley & Sons. (3rd ed. available as a PDF)
  • Emsley, John (1998). The Elements (3rd ed.). Oxford: Clarendon Press.
  • Maxwell, George (2008). Chemistry Demonstrations For High-School Teachers. ISBN 9780955684302.
  • Patnaik, Pradyot (2002). Handbook of Inorganic Chemicals. McGraw-Hill. ISBN 0-07-049439-8.
  • Shakhashiri, Bassam Z. (1983). “Reaction of Potassium Chlorate and Sugar.” Chemical Demonstrations: A Handbook for Teachers of Chemistry, Volume 1. Madison: The University of Wisconsin Press. pp. 79-80.
  • Windholz, Martha (ed.) (1983). The Merck Index (10th ed.). Merck & Co., Inc.