Cola-Mentos-Fontäne

A Diet Coke and Mentos eruption (also known as a Mentos eruption, soda geyser or just Diet Coke and Mentos) is a reaction between Mentos candy and cola. The experiment involves dropping several Mentos candies (usually 5–8) into a bottle of diet cola, (note: normal cola can still be used), resulting in an eruption occurring because of rapidly expanding carbon dioxide bubbles on the surface of the Mentos. Producing the reaction has become a popular science experiment and an Internet meme, with videos of Mentos eruptions and even Mentos performance art pieces being posted on sites like Google Video and YouTube.

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

History

Steve Spangler initiated the huge Internet phenomenon when he appeared on 9News in 2002 and 2005, both times showcasing the experiment. A video of his September 2005 appearance, which resulted in one of the anchors being drenched in Coke, was placed on their website and video sharing website, YouTube.

The experiment was then further popularized by the website Eepybird.com, which promoted a video in which two men re-created the fountain display seen 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. In September 2007, the videos, including the "Extreme Diet Coke and Mentos Experiments" video that was viewed more than 10 million times, earned the pair the highest annual payout of US$50000 from the video hosting service Revver.

The eruption has been reproduced many times by popular sources, including the television show MythBusters and an appearance by cast member Kari Byron in FHM magazine, an appearance on the Late Night With David Letterman by student Lee Marek, and others. MythBusters later created what is believed to be the biggest soda geyser recorded, at over 29 feet (9 meters), using a nozzle.

The World Record for simultaneous Mentos Eruptions was set on September 15, 2007 in Breda, The Netherlands during a special event organized by Mentos. Guinness World Records certified the record-setting effort, when 853 volunteers simultaneously dropped 4265 Mentos into two-liter bottles. The new world Record beat the former record set on July 10, 2007 in Flower Mound, Texas where 791 Mentos-and-Coke geysers were set off.

Explanation

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. Water molecules strongly attract each other, linking together to form a tight connection 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 gellan gum and gum arabic of the candy dissolves and breaks the surface tension. This disturbs the water connection, 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 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. The experiment was also repeated in an episode from Numb3rs.

Variations

Vorlage:Unreferencedsect The experiment 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 anywhere from 1½ m to 30 m in the air. Alternatively, the mentos can be taped or smashed onto the underside of the cap, which can then be screwed back on without the Mentos touching the Diet Coke. Another alternative is inserting the Mentos packet (with the wrapping still on) and then shaking the bottle. This gives the person time to shake the bottle before it explodes as the paper wrapping serves as a barrier.

Anyone attempting to put the cap back on to a bottle after the Mentos has been added should be very careful. The amount of pressure created by this reaction is enough to rupture the sides of the bottle, creating an explosion rather than an eruption or rocket (See dry ice bomb).

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. However when attempting to create a "Mentos rocket," freezing the Mentos proves counter-productive, as the reaction occurs too quickly to re-cap the bottle. 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 variety is the best choice, because they have a matte finish (better for reaction), whereas the finish on the fruit Mentos is a gloss finish.

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 evidenced by numerous online videos), no actual news accounts exist of anyone dying from it. However, eating Mentos and drinking Diet Cola in a short timeframe is not an advisable course of action. This theory has also been tested on the Discovery series Mythbusters. They used a human analogue consisting of a pig's stomach with tubing that allowed for the insertion of the Coke and Mentos. The resulting expansion, however was not enough to rupture the stomach.

See also

• Dry ice bomb
• Chlorine bomb
• Nucleation
• "Diet Coke and Mentos", the MythBusters episode chronicling the experiment

Further reading

• John E. Baur, Melinda B. Baur, The Ultrasonic Soda Fountain: A Dramatic Demonstration of Gas Solubility in Aqueous Solutions, Journal of Chemical Education, vol 83 no 4, April 2006, pp577–580

External links

• Various Videos of the "Mentos Eruption" at YouTube
• About.com Chemistry page with instructions
• Eepybird, official site
• Cocamentos, official european site, soon available in english
• Coke Rocket Bros videos of experiments with Coke and Mentos

• Planet Mentos - Mentos eruption pics on flickr
• Mentos Reaction Explained