“Devil’s Toothpaste” is a popular science experiment known for its visually striking, foamy eruption, often also called “Elephant Toothpaste.” This demonstration showcases a rapid chemical reaction that produces a large volume of foam, resembling an oversized tube of toothpaste.
Gathering Your Supplies
To perform the Devil’s Toothpaste experiment, you will need several readily available materials, with some variations depending on the desired scale and intensity of the reaction. The primary chemical reactant is hydrogen peroxide (H₂O₂), which can be found in various concentrations. Household hydrogen peroxide is typically 3%, while drugstore versions might be closer to 6%. For a more dramatic effect, higher concentrations like 30% or 35% are used, often sold as hair bleach or pool shock, but these require significantly more caution.
A catalyst is essential to speed up the reaction. Common catalysts include a solution of potassium iodide (KI) or a mixture of warm water and dry yeast. Dish soap is also necessary, as it traps the gas produced during the reaction, creating the characteristic foamy structure.
You will also need a container with a narrow opening, such as a plastic bottle or a graduated cylinder, to direct the foam upwards. Food coloring can be added for visual appeal, creating colorful stripes or a uniform vibrant foam.
Creating the Reaction
Begin by setting up your workspace in an area that can tolerate spills, such as a large tray or outdoors. Pour approximately ½ cup of hydrogen peroxide into your chosen container. If using food coloring, add several drops directly to the hydrogen peroxide. For striped foam, allow the food coloring to drip down the inside walls of the container without mixing.
Next, add a generous squirt of liquid dish soap to the hydrogen peroxide solution and gently swirl the mixture to combine them. In a separate small cup, prepare your catalyst. If using yeast, combine one tablespoon of dry yeast with three tablespoons of warm water and stir for about 30 seconds until it forms a slurry. If using potassium iodide, prepare a saturated solution by dissolving the solid in water.
Once the catalyst is ready, quickly pour the entire catalyst mixture into the hydrogen peroxide solution in the main container. Immediately step back and observe the rapid eruption of foam. The reaction typically proceeds quickly, with foam rising and expanding out of the container.
Understanding the Science
The Devil’s Toothpaste experiment demonstrates the rapid decomposition of hydrogen peroxide (H₂O₂). Hydrogen peroxide is a compound that naturally breaks down into water (H₂O) and oxygen gas (O₂), but this process is usually very slow.
A catalyst is introduced to significantly speed up this decomposition reaction without being consumed in the process. When yeast is used as the catalyst, an enzyme called catalase, present within the yeast cells, facilitates the breakdown of hydrogen peroxide. Similarly, when potassium iodide is used, the iodide ion acts as the catalyst.
As the hydrogen peroxide rapidly decomposes, a large volume of oxygen gas is produced. The dish soap mixed with the hydrogen peroxide traps this newly formed oxygen gas, creating numerous bubbles that expand into the voluminous foam. This reaction is also exothermic, meaning it releases heat, which can make the container and the foam feel warm or even hot to the touch.
Safety and Responsible Cleanup
Safety is paramount, especially with higher concentrations of hydrogen peroxide. Hydrogen peroxide solutions, particularly those above 6%, can cause skin irritation, chemical burns, and severe eye damage. Always wear safety goggles and gloves throughout the process.
Adult supervision is necessary for this experiment, especially when working with children or higher peroxide concentrations. Adequate ventilation is also advisable to avoid inhaling any released vapors. After the reaction subsides, allow the foam to cool before handling.
For cleanup, the resulting foam is primarily water, soap, and oxygen. The byproducts are generally considered safe to dispose of by washing them down the drain with plenty of water. However, ensure that any unreacted hydrogen peroxide is thoroughly diluted. Spills on surfaces can be cleaned with wet paper towels, and all equipment can be washed with warm, soapy water.