Elephant toothpaste a fun and colourful chemical reaction

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Elephant toothpaste a fun and colourful chemical reaction

This experiment is a great example of a decomposition reaction! This is a chemical reaction where a chemical, made up of a single molecule breaks down into two different molecules. In addition, this is also an example of an exothermic reaction which means it gives off heat. It’s called elephant toothpaste because the reaction looks like toothpaste oozing out of a tube, big enough to brush an elephant’s teeth!

I have seen this experiment on Pinterest lots of times but have never attempted it before. I was put off by the need to use an ingredient that came from a chemist, which meant that I had to remember to get it outside of a normal grocery run. Also a lot of the recipes are American which means that the measurements aren’t metric and it all just seemed a bit too hard.

If that is you too, then now is the time to give this a go, the peroxide is easily available in Australian chemists, and despite my concern, they knew what I was talking about when I asked for it. Also having done it with Ethan and Lily, I can assure you that it is safe even if they stick their fingers in it, which both of my kids did – but make sure that they wash their hands quickly as it can’t be great for the skin and you don’t want peroxide on their clothes or any fabric in the house.

We had a lot of fun doing this experiment. Because of the overflow, we did in in the garden on an old plank of wood so that the mess wouldn’t matter. 

Ethan was mesmerized and wanted me to do it again but sadly I had only bought a very small bottle of hydrogen peroxide so we will have to save this one to do again another day.

Materials

  • Small cup
  • 125mL empty plastic bottle (the little pop-top bottles are perfect)
  • 60ml 20% (or greater) hydrogen peroxide*
  • 1½ Tsp dry yeast
  • 1Tbs warm water (warm tap water is fine. Don’t use boiling water as it kills the yeast)
  • 1½Tsp Dishwashing liquid
  • Food colouring (optional but makes it pretty)

*You need to get the hydrogen peroxide from the chemist or a hairdressing supplies store like Hair Warehous as the ones they have at the supermarket are not strong enough. You find the peroxide on the shelves with the general hair dying kits. I had to ask someone to give me a hand to locate it at my local chemist and they were happy to help.

Method

  1. Carefully pour the hydrogen peroxide into the bottle. It is best if this is done by an adult.
  2. Add approximately 4 drops of food colouring.
  3. Add the dishwashing liquid, put the cap on and give the bottle a gentle shake to mix it.
  4. In the small cup, mix the warm water with the yeast for 30 seconds.
  5. Pour the yeast mixture into the bottle and watch the foamy reaction! Make sure to do it over a surface you don’t mind getting dirty as this experiment is very messy. 

The Science

The dry yeast contains an enzyme called catalase. Catalase is found in our liver and is used to break down the hydrogen peroxide into water and oxygen. This is the decomposition part of the reaction. The foam produced is lots of tiny bubbles filled with the oxygen from the reaction. The detergent helps to exaggerate the size and number of the bubbles in the reaction.

During the reaction the bottle becomes warm, indicating that this particular reaction is exothermic.

If you like exploring chemical reactions with your kids, try these other experiments:

Magic milk, fizzy bath bombs, naked eggs, lava lamps and invisible ink


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