Mentos eruption

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A handful of Mentos in a two liter Diet Coke bottle produces an eruption.

A Mentos eruption (also known as a Mentos and Diet Coke geyser, Soda Geyser) has become a backyard science experiment fad first demonstrated by "science guy," Steve Spangler. It has also become an internet phenomenon, with videos of Mentos eruptions and even Mentos performance art pieces being posted on sites like Google Video and YouTube.

The experiment involves dropping several Mentos candies (usually 5–8) into a bottle of diet cola, resulting in an eruption. This reaction is thought to occur because of rapidly expanding carbon dioxide bubbles inside once the Mentos are introduced to the carbonation.

This can be done in reverse, forming a Mentos rocket. Typically a two liter bottle is used, with the cap replaced after dropping several Mentos in. The bottle is then shaken up and thrown on the ground, cap-down. If the bottle hits the ground hard enough to let the pressure break the cap off, the bottle will launch like a rocket.

Mentos geysers have been used in Internet humor; the epitome of the concept came from Eepybird.com, which promoted a video in which two men re-created the fountain display in front of the Bellagio in Las Vegas, NV using a timed series of Mentos geysers. Later Eepybird videos featured "self-actuating" Mentos geysers linked together to form a Domino Rally-style effect.

The biggest soda geyser recorded is 34 feet (10.4 meters) as accomplished by the television show, Mythbusters. This beat the previous unofficial record of 18 feet (5.5 meters) by Steve Spangler, who has also produced equipment to easily reproduce the experiment for kids.^[1] One way to improve height of a Mentos reaction with Diet Coke is by freezing the Mentos. Gum arabic, like water, expands when it freezes, which allows the reaction to happen at a quicker rate, because the Mentos become more porous. Rock salt can also be used to produce a reaction of great height, because of the ions in the salt. A nozzle on the bottle is also effective for increasing the height of the reaction. When using Mentos, the Mint kind is the best choice, because they have a matte finish (better for reaction), whereas the finish on the fruit Mentos is a gloss finish.

1 Explanation
2 Urban Legends
3 Notes(just notes)
4 See also
5 Further reading
6 External links

[edit] Explanation

The geyser produced can be several meters high.

While there are various theories being debated as to the exact scientific explanation of the phenomenon, many scientists claim that it is a physical reaction and not a chemical one.^[2] Water molecules strongly attract each other, linking together to form a tight mesh around each bubble of carbon dioxide gas in the soda. To form a new bubble, water molecules must push away from one another. It takes extra energy to break this surface tension. So, in other words, water resists the expansion of bubbles in the soda.

When Mentos are dropped into soda, the gelatin and gum arabic of the candy dissolves and breaks the surface tension. This disturbs the water mesh, so that it takes less work to expand and form new bubbles. Each Mentos candy has thousands of tiny pores all over its surface. These tiny pores function as nucleation sites, perfect places for carbon dioxide bubbles to form. As soon as the Mentos enter the soda, bubbles form all over their surface. They quickly sink to the bottom, causing carbon dioxide to be released by the carbonated liquid with which they come into contact along the way. The sudden increase in pressure pushes all of the liquid up and out of the bottle.

The reaction was the subject of an August 9, 2006 episode^[3] of MythBusters, a television program on the Discovery Channel. They concluded that the caffeine, potassium benzoate, aspartame, and CO₂ gas contained in the Diet Coke and the gelatin and gum arabic ingredients of the Mentos all contribute to the geyser effect. In addition, the MythBusters theorized that the physical structure of the Mentos is the most significant cause of the eruption. When flavored Mentos with a smooth waxy coating were tested in carbonated water, no reaction occurred, whereas standard Mentos added to carbonated water formed a small geyser, by their claim, affirming the nucleation-site theory. Of course a wax coating would render just about anything inert in this experiment; wax-coated sodium would have given the same reaction. This was further supported when rock salt was used as an effective substitute for Mentos.^[4]

The reason that people use diet sodas is because they do not contain sugar like regular cola. Non-diet sodas contain a large percentage of sugar molecules, which help hold onto the carbon dioxide a lot better, thus preventing nucleation from occurring as quickly, resulting in a weaker reaction. Also, the fact that diet sodas do not contain sugar means that the resulting mess after the geyser, which may be liberally splattered all over the surrounding area, will not be sticky as the residue from a non-diet drink would be. This makes cleanup much easier.

[edit] Urban Legends

In November, 2006, the Urban Legends Reference Pages examined the rumors of people dying from eating Mentos and drinking cola. Their research found that while eating Mentos and drinking cola can result in people regurgitating the foamy result (as evinced by numerous online videos), no actual news accounts exist of anyone dying from it.^[5]