30% Hydrogen peroxide is added to a Potassium Iodide catalyst, detergent and food colouring, and Oxygen bubbles rapidly produce a foam.

A small teaspoon of solid Potassium Iodide, a squirt of detergent, and a few drops of food colouring are put into a measuring cylinder of any size placed into a tray. 30% Hydrogen Peroxide is added, and coloured foam is formed rapidly, spurting out of the top.

📄 With 3% Hydrogen Peroxide and yeast catalyst: https://www.sciencebuddies.org/stem-activities/elephant-toothpaste
📄 With 30% Hydrogen Peroxide and Potassium Iodide catalyst: https://www.thoughtco.com/elephant-toothpaste-chemistry-demonstration-604250
🎞️ A very large example in a swimming pool: https://www.youtube.com/watch?v=Kou7ur5xt_4
🎞️ World's Tallest: e09xig209cQ

• Using 3 or 6% Hydrogen Peroxide will make the foam form much slower, but it will still overflow the measuring cylinder.
• Using a conical flask instead of measuring cylinder can make the foam shoot higher, and it can reach the roof.
• Putting a glowing splint into the foam afterwards can make it glow brighter, but the foam also helps to extinguish it so it probably can't be made to relight.

Safety glasses required Gloves may be worn

1. What is the reaction occurring?
2. What gas is produced?
3. What is the evidence of a gas being produced?
4. What is the evidence of a chemical change?
5. How does the concentration of the Hydrogen Peroxide affect the reaction rate?

[Things to consider for further investigation here