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: https://www.youtube.com/watch?v=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
  
• Student should stand back at least 1 metre
  
• Gloves may be worn
  

• What is the reaction occurring?
• What gas is produced?
• What is the evidence of a gas being produced?
• What is the evidence of a chemical change?
• How does the concentration of the Hydrogen Peroxide affect the reaction rate?

• Compare the reaction rate with several different concentrations of Hydrogen Peroxide.
• Compare the reaction rate between using a sold Potassium Iodide, aqueous Potassium Iodide, or Yeast catalyst.
• Use different colours of food colouring, or a different colour on each side of the measuring cylinder.