Science Video – Elephant’s Toothpaste, A Reaction Using A Catalyst

by

Your KS3 students will enjoy watching this video showing an very exciting example of a chemical reaction using a catalyst.

This video shows an exciting example of how a catalyst greatly increases the rate of a reaction. The name ‘elephant’s toothpaste’ comes from the fact that the column of foam produced during the reaction resembles toothpaste from a large tube (kind of!).

Elephant’s toothpaste

The demonstrator in the video explains what each substance in the reaction is used for. The hydrogen peroxide (H2O2) is added first and this will be split up to produce water and oxygen.

Washing up liquid is added to trap the bubbles of oxygen produced and food colouring is there to make the foam coloured. Students need to understand that these substances take no part in the chemical reaction but are there to make lots of colourful foam, which adds the ‘wow’ factor.

At this point, the chemical reaction is taking place in the flask but at a very slow rate. Bubbles of oxygen cannot be seen. A catalyst is needed to speed up the reaction, and this is added at the end. The result of the addition of the catalyst is clearly visible and the foam shoots up out of the flask as oxygen is released from the hydrogen peroxide at a very fast rate.

After your students have watched the video you could ask them some of these questions:

What is the word and balanced symbol equation for the reaction?

Hydrogen peroxide –> hydrogen + oxygen

2H2O2 –> 2H2O + O2

How can you tell from the video that this reaction is exothermic?

You can see steam being released from the foam. Water is produced during the reaction which is turned to steam because of the heat released during the reaction.

What does this demonstration show about the effect of a catalyst on a reaction?

A catalyst will increase the rate of a reaction. We can see this in the demonstration because before the catalyst is added the reaction is so slow that we can’t see the oxygen being produced. As soon as the catalyst is added oxygen is made at a very fast rate and produces a large volume of foam which shoots out of the flask.

Further Resources

Your students can find out how a catalyst has helped solve one of our biggest environmental problems by taking a look at the article Oops! When science goes wrong – How catalysts can help reduce pollution.