2 H2O2(aq) O2(aq) + 2 H2O(aq)A foam of oxygen bubbles and soap will rise quickly up the cylinder and out the top, like toothpaste squirting out of a tube. (Let a little food dye run down the sides of the cylinder before you add the iodide, so the foam comes out of the tube striped like toothpaste.)
You may be wondering why there isn't any iodide in the reaction above. The iodide acts as a catalyst- that is, it speeds up the reaction without being produced or consumed in the reaction. Manganese dioxide can also be used as a catalyst.
This demonstration is potentially dangerous. Wear gloves and goggles. 30% hydrogen peroxide solution can cause serious burns and damage to the eyes. It can also bleach hair and clothing. If you add too much iodide, the peroxide may spray violently out of the top of the tube- and all over you and your audienc.
|The recipe for the "elephant's toothpaste" demonstration- a classic! This student-constructed site also includes a RealMedia clip of the demonstration in action.|
Author: Fred Senese firstname.lastname@example.org
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Last Revised 08/17/15.URL: http://antoine.frostburg.edu/chem/senese/101/redox/faq/print-elephants-toothpaste.shtml