Dinosaur Toothpaste

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

To speed up a reaction without altering the chemistry of 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. Are you ready?

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2 Responses to “Dinosaur Toothpaste”
  1. Aurora says:

    This is one of the experiments that we’re still working on. We’re in the middle of creating 700 more worksheets to post to the website, and this is one of them. So you don’t have to wait, here’s what I would do: make yourself a data table and think of one thing you’d like to change (incrementally – one small bit at a time) so you can see how it affects the experiment. Near the end of the video I’ve given a suggestion for one thing I changed, but you can vary the amount of H2O2, or yeast, or temperature of the liquid, size of the container… etc. Do at least three trials, and then you can make a statement (conclusion) about what you learned.

  2. tsyed says:

    where can I find the worksheet for this experiment?

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