Elephant's toothpaste is a foamy substance caused by the rapid
decomposition
Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...
of
hydrogen peroxide
Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%†...
() using
potassium iodide
Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are us ...
(KI) or
yeast
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...
and warm water as a
catalyst
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
. How rapidly the reaction proceeds will depend on the
concentration
In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', ''molar concentration'', ''number concentration'', an ...
of hydrogen peroxide.
Because it requires only a small number of ingredients and makes a "volcano of foam", this is a popular experiment for children to perform in school or at parties. The experiment is also known as the "marshmallow experiment", but is unrelated to the psychological
Stanford marshmallow experiment
The Stanford marshmallow experiment was a study on delayed gratification in 1972 led by psychologist Walter Mischel, a professor at Stanford University. In this study, a child was offered a choice between one small but immediate reward, or two sm ...
.
Explanation
Description
About 50 ml of concentrated (>12%) hydrogen peroxide is first mixed with liquid soap or dishwashing detergent. Then, a catalyst, often around 10 ml
potassium iodide
Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are us ...
solution or
catalase
Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting t ...
from
baker's yeast
Baker's yeast is the common name for the strains of yeast commonly used in baking bread and other bakery products, serving as a leavening agent which causes the bread to rise (expand and become lighter and softer) by converting the fermentable ...
, is added to make the hydrogen peroxide decompose very quickly. Hydrogen peroxide breaks down into oxygen and water. As a small amount of hydrogen peroxide generates a large volume of oxygen, the oxygen quickly pushes out of the container.
The soapy water traps the oxygen, creating bubbles, and turns into foam.
About 5-10 drops of food coloring could also be added before the catalyst to dramatize the effect. How rapidly the reaction occurs will depend on the concentration of hydrogen peroxide used.
Chemical explanation
This experiment shows the catalyzed decomposition of hydrogen peroxide. Hydrogen peroxide (H
2O
2) decomposes into water and oxygen gas, which is in the form of foam, but normally the reaction is too slow to be easily perceived or measured:
:
2H2O2 -> 2H2O + O2 ^
In normal conditions, this reaction takes place very slowly, therefore a catalyst is added to speed up the reaction, which will result in rapid formation of foam. The iodide ion from potassium iodide acts as a
catalyst
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
and speeds up the reaction while remaining chemically unchanged in the reaction process.
The iodide ion changes the mechanism by which the reaction occurs:
:
The reaction is
exothermic
In thermodynamics, an exothermic process () is a thermodynamic process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), electricity (e ...
; the foam produced is hot.
A glowing splint can be used to show that the gas produced is oxygen.
The rate of foam formation measured in volume per time unit has a positive correlation with the peroxide concentration (v/V%), which means that the more reactants (peroxide concentration) the faster the rate of foam formation.
Variations
YouTube
YouTube is a global online video platform, online video sharing and social media, social media platform headquartered in San Bruno, California. It was launched on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim. It is owned by ...
science entertainer
Mark Rober
Mark B. Rober is an American YouTuber, engineer, inventor, and educator. He is known for his YouTube videos on popular science and do-it-yourself gadgets. Before YouTube, Rober was an engineer with NASA for nine years, where he spent seven y ...
has created a variation of the experiment, named "Devil's Toothpaste", which has a far more pronounced reaction than the version usually performed in classroom settings.
The ingredients to create the devils toothpaste reaction are the same as the regular elephants toothpaste reaction, the only difference being that 50% H202 instead of the usual 35%
See also
*
Black snake (firework)
"Black snake" is a term that can refer to two similar types of firework, the Pharaoh's snake and the sugar snake. The "Pharaoh's snake" or "Pharaoh's serpent" is the original version of the black snake experiment. It produces a more impressive ...
*
Carbon snake
Carbon snake is a demonstration of the dehydration reaction of sugar by concentrated sulfuric acid. With concentrated sulfuric acid, granulated table sugar ( sucrose) performs a degradation reaction which changes its form to a black solid-liqu ...
*
Soda geyser
diet Coke Mentos.jpg, A bottle of Diet Coke just after Mentos were dropped into it
shimadaK2007Sept09-MentosGeyser DSC 3294++.JPG, From left to right: action of five Mentos candies (per bottle) with Perrier, classic Coke, Sprite, and Diet Coke ...
References
External links
{{commons category, Elephant toothpaste
The Elephant's Toothpaste Experimentsciencebob.com
Chemistry classroom experiments
Articles containing video clips