Soda geyser

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

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 (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 websites like Google Video and YouTube.

History

Steve Spangler initiated the huge Internet phenomenon when he appeared on Denver's KUSA-TV 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 yearly 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 Show 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.

Explanation

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 popular 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 of Numb3rs.

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. Also, on the episode where they found out what causes the eruption, one of the hosts drank the mixture and ended up spitting it out.

Records

The official record for the most fountains set off at once is 850 and was set by a group of people in Breda, The Netherlands. Recently, over 1000 people, along with KFVS-TV of Cape Girardeau, Missouri set off 1000 fountains at once. This event was completed on October 3rd and documentation is being sent to the Guinness Book Of World Records for verification.

See also

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

• Alka-Seltzer rocket
• Water rocket

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