Things you will need:

  • 20-volume (or 40-volume) developer, which is a 6% (or 12%) hydrogen peroxide solution. You’ll likely need to go to a beauty supply store to find this. The hydrogen peroxide from a drug store (the one in the brown bottle) is usually 3%, which is not concentrated enough to have quite the same effect.
  • Dry yeast
  • Liquid dish soap
  • Bottle with a narrow opening (think soda bottle or something similar)
  • Normal kitchen gear: water, small cup, etc.

What to do:

  • Pour 1/2 c of the hydrogen peroxide in a bottle.  You can add food coloring here if you want, but we didn’t
  • Add about 1 Tbs of liquid dish soap to the same bottle
  • In a cup, mix together 1 Tbs dry yeast with about 3 Tbs warm water and stir it for about 30 seconds
  • Pour the yeast mixture into the bottle containing hydrogen peroxide and dish soap
  • Watch and cheer! Hooray!

Safety notes:

  • Hydrogen peroxide can irritate skin and eyes, so do handle carefully. Gloves and goggles are a good idea.
  • The reaction will produce some heat and will also probably overflow the bottle, so set the bottle down on a surface that is okay to get wet and soapy

Here is what’s happening: What you’re observing is a catalyzed chemical reaction. This is a decomposition reaction where one compound decomposes or breaks apart.  In this case, we see hydrogen peroxide (H2O2) decompose into oxygen (O2) and water (H2O). The reaction looks like:  2H2O2 –> 2H2O (liquid) + O2 (gas)

Because oxygen is a gas, it bubbles up through the water and foams out of the bottle (as it mixes with the soap that you added). You might notice that the yeast isn’t part of the equation that we wrote, but there is a good reason that we added it here. There is a compound in the yeast that acts as a catalyst for this reaction. Catalysts are compounds that increase the rate of a reaction without changing themselves or changing the products of the reaction. They basically are there to speed things up. Hydrogen peroxide will decompose on its own without the catalyst from yeast, but it happens slowly over time. This is why you might need to get a new bottle of hydrogen peroxide from the drug store if you’ve had yours for a while – eventually it will just be a bottle of water. The catalyst speeds this whole reaction up to happen in a few seconds, though, which makes it much more exciting than what would happen on its own in your medicine cabinet.