Elephant’s Toothpaste

Introduce your students to the concept of chemical reactions with this classic hands-on experiment!

Concepts

chemical reactions, exothermic reactions

Grades: 6-8

Materials

  • clear plastic bottles
  • 1/2 cup of 6% hydrogen peroxide
  • 1 tablespoon of dry yeast (1 packet)
  • 3 tablespoons of warm water (fills the bottle about 1/5 the way)
  • liquid dish soap
  • food coloring
  • plastic cup
  • Popsicle sticks/wooden stir sticks
  • foil cake pans, or large shallow containers to contain the mess
  • a funnel
  • Safety goggles

Steps

  1. Begin by placing a clear plastic bottle into the foil cake pan. Unscrew and remove the bottle cap.
  2. Place a plastic funnel into the bottle and grab the hydrogen peroxide
    • (Note: for larger classes, peroxide can be measured out prior to the experiment and provided to students in small plastic cups. For younger students, the teacher should pour the peroxide into the bottle.)
  3. Hold the funnel with one hand and carefully pour the peroxide into the bottle.
  4. Add a squirt of liquid dish soap into the bottle. Swish the bottle gently to mix the solution together.
  5. Add a few drops of food coloring. Colors can be added as desired. Swish the bottle if a consistent color is desired.
  6. In a plastic cup, mix together warm water and dry yeast. Use the stirring stick to mix the solution together. The consistency should be a semi-thick liquid free of large lumps.
  7. When you are ready to begin the reaction, quickly but carefully pour the yeast-water solution into the funnel. Quickly remove the funnel and watch the reaction!

What happened here?

This experiment represents a chemical reaction, when two or more ingredients mix together and the chemical components are changed, thus creating something new. This reaction in particular is an exothermic reaction, meaning it produced energy in the form of heat.

The yeast is a catalyst which increased the rate of the reaction. The yeast quickly removed the oxygen from the peroxide, and with the help of the dish soap, produced oxygen-filled bubbles within the foam.

The remaining components of this reaction are water, soap, and oxygen, so it is safe to touch the soap that the reaction produced (but don’t ingest it!). You can encourage your students to touch the sides of the bottle so they can feel the warmth produced by the reaction.

Connecting Concepts (NGSS)

PS1.A: Structure and Properties of Matter

  • Each pure substance has characteristic physical and chemical properties (for any bulk quantity under given conditions) that can be used to identify it.

PS1.B: Chemical Reactions

  • Substances react chemically in characteristic ways. In a chemical process, the atoms that make up the original substances are regrouped into different molecules, and these new substances have different properties from those of the reactants.

 

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