Dinosaur Toothpaste Chemistry Experiment

Hydrogen peroxide is used to fuel rockets, airplanes, and other vehicle engines. Chemistry teachers everywhere use it to demonstrate what a catalyst is.

To speed up a reaction without altering the chemistry of what’s going on in the reaction involves adding a catalyst. A catalyst changes the rate of reaction but doesn’t get involved in the overall chemical changes.

For example, leaving a bottle of hydrogen peroxide outside in the sunlight will cause the hydrogen peroxide to decompose. However, this process takes a long time, and if you don’t want to wait, you can simply toss in a lump of charcoal to speed things along.

The carbon is a catalyst in the reaction, and the overall effect is that instead of taking two months to generate a balloon full of oxygen, it now only takes five minutes. The amount of charcoal you have at the end of the reaction is exactly the same as before it started.

A catalyst can also slow down a reaction. A catalytic promoter increases the activity, and a catalytic poison (also known as a negative catalyst, or inhibitor) decreases the activity of a reaction. Catalysts offer a different way for the reactants to become products, and sometimes this means the catalyst reacts during the chemical reaction to form intermediates. Since the catalyst is completely regenerated before the reaction is finished, it’s considered ‘not used’ in the overall reaction.

In this experiment, you’ll see that there’s a lot of oxygen hiding inside the peroxide – enough to really make things interesting and move around! You’ll also find out what happens to soap when you bubble oxygen through it.

The hydrogen is mixed with the soap first. The catalyst (yeast) causes the hydrogen peroxide to break down into oxygen and water. Since there’s a lot of oxygen trapped in the peroxide, this decomposition happens very quickly and the oxygen rushes out of the container fast! As this happens, the water and soap mix together and turns into foam as the oxygen bubbles through trying to escape.