How do catalysts help chemical reactions happen?
Elephant toothpaste gets its name from the massive amounts of foam it produces. It looks like it could be from a giant tube of toothpaste! This reaction can happen in a few different ways, but today we are going to use yeast as a catalyst - a material to help a chemical reaction happen. We will use some common household chemicals to make a big reaction.
The elephant toothpaste experiment is so dramatic because the reaction happens quickly. Hydrogen peroxide breaks down naturally over time, especially when exposed to light, but in this reaction the yeast causes that breakdown to happen much quicker. This is because yeast is a catalyst - a substance that can help the reactants react to each other faster, without becoming part of the end products of the reaction. Catalysts were first written about in 1794 by a Scottish chemist named Elizabeth Fulhame. She was writing about chemical reactions used in dyes and paints, and described lots of different ways that metals and other materials interact. Since then, chemists and engineers have discovered lots of other ways to use catalysts, and they help make many materials that we use today. Yeast is a naturally occurring catalyst that is good at breaking down hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2). In this experiment, we will see how that process looks when it happens quickly.
You should see the mixture start to foam and shoot out the top of the plastic bottle. This is happening because the hydrogen peroxide is breaking down into water and oxygen very quickly due to the yeast. The yeast is acting as a catalyst to speed up the reaction. The oxygen gas takes up a lot more space than when it was in liquid form, so it starts to leave the bottle. The foam is caused by the dish soap forming bubbles with the oxygen as it is produced.
You may have also noticed some steam coming off of the foam, or that it feels warm to the touch. That is because this reaction is exothermic - it releases heat as a form of energy. It takes more energy to hold the molecules together in the form of hydrogen peroxide than it does to hold the oxygen and water molecules together, so when the peroxide molecules break up, that extra energy has to go somewhere. It gets released as heat.
Be sure to clean up when you are done. Your mixture can be dumped down the sink, and all of the containers and measuring tools you used can be washed and put away. Make sure to clean up any mess that was left on the ground or floor as well.
This experiment was selected for Science at Home because it teaches NGSS Disciplinary Core Ideas, which have broad importance within or across multiple science or engineering disciplines.
Learn more about how this experiment is based in NGSS Disciplinary Core Ideas.