Mad Science: Kid Friendly Elephant Toothpaste

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Supplies

  • 16 oz empty plastic soda bottle (preferably with a narrow neck such as those made by Coca-Cola)
  • 1/2 cup 20-volume hydrogen peroxide (20-volume is 6% solution, purchased from a beauty supply store)
  • Squirt of Dawn dish detergent
  • 3-4 drops of food coloring
  • 1 teaspoon yeast dissolved in approximately 2 tablespoons very warm water
  • Funnel
  • Foil cake pan with 2-inch sides
  • Safety glasses
  • Lab smock

Process

  1. Have students put on their safety glasses and lab smock.  Each student should have in front of them a cake pan, plastic bottle, Dawn in small cup, food coloring, 1/2 cup peroxide, and the dissolved yeast mixture.
  2. Stand the bottle up in the center of the cake pan. Put the funnel in the opening. Add 3-4 drops of food coloring to the peroxide and pour the peroxide through the funnel into the bottle. Show a water molecule diagram and a peroxide molecule diagram, pointing to the extra oxygen that will be set free in the reaction.
  3. Add the Dawn detergent to the peroxide in the bottle.
  4. Pour the yeast mixture into the bottle and quickly remove the funnel.
  5. The students can touch the bottle to feel any changes that take place.

What’s Happening

The reaction creates foam that shoots up out of the bottle and pools in the pan. After a minute or so, it begins to come out in a moving stream that looks like toothpaste being squeezed out of a tube. The students can play with the foam as it is just soap and water with oxygen bubbles. The bottle will feel warm to the touch as this is an exothermic reaction.

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