Please be sure to take all safety precautions necessary and wear safety glasses!

Elephant Toothpaste

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Published: 11/01/2007 9:28 am

Updated: 11/05/2007 5:57 pm

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Materials:	Hazards: 1. Wear safety goggles. Also, wear disposable gloves when pouring 30% hydrogen peroxide, as it is a very strong oxidant. 2. Do not stand over the graduated cylinder because steam and oxygen are produced quickly. **THIS IS AN EXPERIMENT FOR SCIENCE TEACHERS. CHEMICALS USED IN THIS EXPERIMENT ARE DANGEROUS.
Tall graduated cylinder (at least 500 ml})
Food coloring
10ml Liquid soap
100ml 30% hydrogen peroxide (H₂0₂)
10ml Saturated solution of potassium iodide (KI)
Rubber gloves & Safety glasses
1 Plastic Garbage Bag

Procedure:
Place the graduated cylinder on an open garbage bag. Fill the cylinder about 1/4 full with the 30% hydrogen peroxide. Add teh 10ml of liquid soap. Put some food coloring on the inside wall of the cylinder. Add 10ml of saturated potassium iodide.

(Note: A saturated solution of potassium iodide is made by dissolving 100g of potassium iodide in 70 ml of water. Store for future use.)

What's Going On:
This experiment demonstrates the decomposition of hydrogen peroxide catalyzed by potassium iodide. The rapid production of oxygen causes the mixture to foam. Wow, it really foams!

The 2-step decomposition reaction is written as follows:

a. H₂0₂(aq) + I - (aq) H₂OI + OI - (aq)
(rate determining step)

b. H₂O₂(aq) + OI - (aq) H₂OI + O₂(g) + I - (aq)

This foam, because of the iodine, will stain clothes and skin. Please wear safety glasses and don't use the foam as toothpaste.

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