Elephant Toothpaste

Rapid catalytic decomposition of hydrogen peroxide producing a massive foam column

Classroom Demonstrations Beginner (Middle School) 20 min ~$10.00

Objective

Demonstrate the catalytic decomposition of hydrogen peroxide using potassium iodide, illustrating concepts of catalysis, exothermic reactions, and gas evolution.

Background

Elephant toothpaste is one of the most popular chemistry demonstrations. Concentrated hydrogen peroxide (H₂O₂) is decomposed rapidly by a potassium iodide (KI) catalyst, releasing oxygen gas and steam. When performed in a narrow-neck flask with dish soap, the oxygen gas creates a towering column of foam that erupts like giant toothpaste. The reaction is exothermic, and the foam is warm to the touch. The iodide ion acts as a catalyst by cycling between I⁻ and IO⁻ intermediates.

Safety Warnings

  • 30% H₂O₂ causes severe skin burns and eye damage
  • Wear face shield and heavy-duty gloves
  • Do not stand over the flask when adding KI
  • The foam is hot — do not touch immediately
  • Perform behind a safety shield

Required PPE

goggles gloves lab_coat face_shield

Materials

  • Hydrogen peroxide (30%) (50 mL)
    30% concentration required for dramatic effect
  • Potassium iodide (KI) (10 g)
    Dissolved in 25 mL water
  • Liquid dish soap (15 mL)
  • Food coloring (5 drops)
    Optional, for visual effect
  • Large tray or bin (1)
    To catch overflow

Equipment

Erlenmeyer flask (1 L, narrow neck) Measuring cylinder Safety shield or splash guard Funnel

Procedure

1

Place the Erlenmeyer flask on the large tray. Set up the safety shield.

2 min Ensure audience is at safe distance
2

Carefully pour 50 mL of 30% H₂O₂ into the flask.

2 min 30% H₂O₂ is extremely corrosive
3

Add 15 mL of dish soap and a few drops of food coloring. Swirl gently to mix.

2 min
4

Dissolve 10 g of KI in 25 mL of warm water. Pour this solution into the flask using a funnel and step back immediately.

2 min Step back immediately after adding
5

Observe the rapid evolution of foam. The reaction is complete in seconds. Discuss the role of KI as a catalyst.

5 min
6

After the foam cools, students may touch it (with gloves). It contains only water, oxygen, soap, and KI — no H₂O₂ remains.

5 min Wait until foam is cool

Expected Results

A dramatic eruption of warm, colored foam that rises 1–2 meters above the flask. Steam may be visible. The reaction demonstrates catalysis (KI is not consumed), exothermic processes, and gas evolution (O₂).

Cleanup

The foam is non-toxic (soap, water, KI). Rinse down the drain with plenty of water. Clean the flask and tray.

Details

Category
Classroom Demonstrations
Difficulty
Beginner (Middle School)
Duration
20 min
Est. Cost
$10.00
Steps
6
Materials
5

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Frequently Asked Questions

What is the objective of Elephant Toothpaste?
Demonstrate the catalytic decomposition of hydrogen peroxide using potassium iodide, illustrating concepts of catalysis, exothermic reactions, and gas evolution.
How difficult is Elephant Toothpaste?
This experiment is rated as Beginner (Middle School). It takes approximately 20 minutes to complete.
What safety precautions are needed for Elephant Toothpaste?
Key safety precautions include: 30% H₂O₂ causes severe skin burns and eye damage; Wear face shield and heavy-duty gloves; Do not stand over the flask when adding KI.
What materials are needed for Elephant Toothpaste?
The main materials required are: Hydrogen peroxide (30%), Potassium iodide (KI), Liquid dish soap, Food coloring, Large tray or bin.
What results should I expect from Elephant Toothpaste?
A dramatic eruption of warm, colored foam that rises 1–2 meters above the flask. Steam may be visible. The reaction demonstrates catalysis (KI is not consumed), exothermic processes, and gas evolution (O₂).