Kids STEM:Hippopotamus Toothpaste

SUPPLIES AND INGREDIENTS:

  • ½ cup 49 Volume Hydrogen Peroxide (*3% solution, first aid quality, will work … it produces a smaller reaction)
  • 1 TBSP liquid dish soap
  • 1 packet (1 TBSP) Active Dry Yeast
  • 4 TBSP warm water
  • Plastic Cup for mixing yeast and water
  • Food coloring
  • Plastic soda bottle (*16 oz. - 1 liter)
  • Washable or protected work surface
  • Foil Tray with high sides and/or Larger cookie sheet or tray with sides
  • Funnel (optional)
  • *Safety goggles (*or … ski/snow goggles, swim goggles) … for general eye protection!

DIRECTIONS:

To make up a batch of hippopotamus toothpaste …

  1. Place the soda bottle in your tray(s) … on a washable, protected surface.
  2. Pour 150 ml (½ cup) of 40 Volume Hydrogen Peroxide into the soda bottle.

    3. (You might want to use a funnel for this!)

  3. Add 1 tablespoon of liquid dishwashing soap to the bottle.
  4. Pour the packet of yeast into the small cup.
  5. Pour 4 tablespoons of warm water over the yeast.
  6. Carefully swirl the cup around to further mix the yeast and water. *It should be the consistency of melted ice cream. Allow about 30 seconds. Add a bit more warm water, if needed.
  7. Dribble several stripes of food coloring down the inside of the soda bottle. This should produce stripes, just like you might see in real toothpaste.
  8. Pour the yeast solution into the soda bottle … and stand back! Watch the mixture expand and foam up.

*Once the chemical reaction is complete, you should have (mostly) just soapy water and yeast. However, if you used the Volume 40 product, and some of the peroxide was unreached in the experiment, it could irritate skin and eyes. For that reason, it’s
recommended that you don’t play with the foam! And DON’T BRUSH ANY TEETH WITH THIS FOAM!

How It Works …

Each tiny foam bubble in this chemical reaction is filled with oxygen. The yeast is a catalyst, a substance that speeds up a reaction. It quickly broke apart the oxygen from the hydrogen peroxide … and that created lots and lots of bubbles! Your experiment not only created bubbles, but also heat … that makes it an EXOTHERMIC reaction.

Clean Up …

It’s safe to use a sponge to wipe up foam from your table surface, and just wash the remaining liquid and foam from the bottle and tray down the sink drain.

Watch this project at: https://youtu.be/N91i9ih62ZM?list=PLMEg2Dd0dSFctLfDQxsL5SmuE8zkwQFmu