Safety InformationHydrogen peroxide is an oxidizer. This demonstration uses a higher concentration of hydrogen peroxide than the home variety, which means you need to wear gloves to protect your hands against an accidental splash or spill, which could cause a burn.
Christmas Tree Elephant Toothpaste MaterialsThere are a few ways to set this up to make a Christmas tree. The key is to add green food coloring to get the tree effect and then either perform the demonstration in an erlenmeyer flask, which naturally produces the tree shape, or else perform the reaction in a tube with a tree template placed over it. You can make a tree shape from aluminum foil, with slots cut up the side and an opening at the top to force the foam from the reaction out into the proper shape.
- 50 ml of detergent
- 100 ml of 30% hydrogen peroxide
- 10 ml of a saturated solution of potassium iodide
- green food coloring
- erlenmeyer flask or homemade Christmas tree model
- Place the erlenmeyer or your Christmas tree container on the lab bench. Add the detergent, peroxide and food coloring.
- Pour the potassium iodide solution into this mixture to catalyze the reaction.
- Optionally, touch a glowing splint to the foam "tree" to relight the splint and demonstrate that the bubbles are filled with oxygen.
ChemistryHydrogen peroxide is catalytically decomposed into water and oxgen. This is a nice example of an exothermic reaction. The audience will be able to see steam rising from the foam.
The overall equation for the elephant toothpaste chemical reaction is:
2 H2O2(aq) → 2 H2O(l) + O2(g)
The decomposition reaction of the hydrogen peroxide into water and oxygen is catalzyed by the iodide ion.
H2O2(aq) + I-(aq) → OI-(aq) + H2O(l)
H2O2(aq) + OI-(aq) → I-(aq) + H2O(l) + O2(g)
Dishwashing detergent is added to capture the oxygen and form bubbles. This is an exothermic reaction which may produce steam.
Kid-Friendly Version of the DemonstrationIf you can't obtain 30% hydrogen peroxide or simply want a demonstration that is safe enough for kids to perform, you can perform an easy variation of this demonstration:
- warm water
- 3% hydrogen peroxide (the type sold at pharmacies)
- pack of active yeast (from a grocery store)
- green food coloring
- In an erlenmeyer or tree-shaped container, mix together 1/4 cup detergent, 1/2 cup of the 3% hydrogen peroxide and several drops of green food coloring.
- In a separate container, stir the packet of yeast into a small amount of warm water. Allow 5 minutes for the yeast to activate before proceeding with the demonstration.
- Perform the demonstration by pouring the yeast mixture into the peroxide and detergent mixture.
2H2O2 → 2H2O + O2(g)
As in the other reaction, the detergent captures the oxygen to form bubbles. Less foam is produced because there is a smaller amount of hydrogen peroxide to decompose.
Learn MoreRed and Green Color Change Christmas Demonstration
Elephant Toothpaste Variations
Borax Crystal Snowflake Decoration