Catalytic Decomposition of H2O2 – Elephant’s Toothpaste Experiment
Elephant's toothpaste is a foamy substance formed as a result of rapid decomposition of hydrogen peroxide. Elephant’s toothpaste reaction experiment is generally used for classroom demonstrations as it requires fewer ingredients and makes a "volcano of foam".
Description:
H2O2 is decomposed by Iodide Ion. Iodide ion is used as a catalyst and these iodide ions come from KI (Potassium Iodide) or NaI (Sodium Iodide). This decomposition reaction liberates water, oxygen and heat.
Materials:
30% H2O2(Hydrogen Peroxide)
1 Liter Graduated cylinder
KI (Potassium Iodide) or NaI (Sodium Iodide).
Food Color for fun
Liquid Dish Detergent
Procedure:
1. Pour 50 mL of 30% H2O2(Hydrogen Peroxide) in 1 L graduated cylinder.
2. Then, add 3-4 drops of food color in 1 L graduated cylinder to make colored H2O2 solution.
3. Then, start adding liquid dish detergent or soap from the side of 1 L graduated cylinder to make a small layer of liquid dish detergent or soap over colored H2O2solution.
4. With the help of small beaker add KI or NaI in the cylinder containing H2O2 solution. As a result of reaction, oxygen gas generated and this gas creates large amount of colored foam. This foam comes out of graduated cylinder.
Discussion:
Decomposition of H2O2(Hydrogen Peroxide) yields O2 (oxygen) and H2O (water). Reaction is catalyzed by I- (Iodide Ion); These Iodide Ion comes from KI or NaI
Reaction-
H2O2 (Aq) + I-1(Aq) ---> H2O(liquid) + IO- (Aq)
IO- (Aq) + H2O2 (Aq) ---> H2O(liquid) +O2 (g) + I-(Aq)
Overall Reaction-
2H2O2 (Aq) ---> 2H2O(liquid) +O2 (g)