One of my favourite demos.
The elephant toothpaste experiment is a popular chemistry demonstration that involves creating a large, foamy eruption of hydrogen peroxide and soap. The experiment is typically performed as follows:
- A large plastic container is filled with hydrogen peroxide, typically at a concentration of 30-35% (50% was used in the video, but this is difficult to find in some countries).
- Food coloring can be added to the hydrogen peroxide to make the reaction more visually appealing.
- A small amount of liquid soap or dishwashing detergent is added to the hydrogen peroxide and swirled around to mix.
- A catalyst, typically potassium iodide is added to the hydrogen peroxide mixture.
- The catalyst initiates a rapid exothermic reaction that breaks down the hydrogen peroxide into water and oxygen gas.
- The soap helps to trap the oxygen gas and create a large foam eruption that resembles toothpaste coming out of a tube.
The reaction produces a large amount of heat and oxygen gas, which can create a spectacular and dramatic display. However, it is important to perform this experiment with caution and under the supervision of a trained professional, as the reaction can be dangerous if not performed properly.
Experimental procedure for the video attached:
The mixture will undergo an exothermic reaction, producing oxygen gas and creating a foam-like substance.
- 500 ml round bottom flask,
- 100 ml of 50% hydrogen peroxide,
- 10 ml washing up liquid,
- 5 g potassium iodide,
- 10 ml water,
- sodium thiosulphate solution,
a. Add 100 ml of 50% hydrogen peroxide and 10 ml washing up liquid to the 500 ml round bottom flask, and mix thoroughly.
b. In a separate beaker, dissolve 5 g of potassium iodide in 10 ml of water.
c. Add the potassium iodide solution to the flask and stand back.
d. Observe the exothermic reaction, which should produce oxygen gas and create a foam-like substance.
e. Clean up any remaining residue using sodium thiosulphate solution.
Results: The reaction should produce a large amount of foam, resembling toothpaste coming out of a tube, as well as heat and oxygen gas.
It is worth noting that this reaction is not a catalytic reaction as the potassium iodide cannot be reused. This experiment can be adapted to show how catalysts affect the reaction rate by replacing the potassium iodide with manganese (IV) oxide (MnO2), yeast or homogenised potato or liver.
Leave a Reply