Diet Coke and Mentos eruption

  A Diet Coke and Mentos Eruption (also known as a Mentos eruption, soda geyser or just Diet Coke and Mentos) is a reaction when an certain objects are dropped into carbonated liquids. The most well-known example of this reaction is the combination of Mentos candy and Diet Coke, typically achieved by dropping several candies into a botle of the cola. A common misconception is that the specific brand of either product is required for the reaction. This results in a jet of cola from the mouth of the bottle due to the rapid expanding of carbon dioxide bubbles on the surface of the candy. Producing the reaction has become a popular science experiment and an Internet meme, with videos of eruptions and even performance art pieces being posted on websites like Google Video and YouTube.

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History

Steve Spangler initiated the 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^[1] appearance, which resulted in one of the anchors being drenched in Coke, was placed on their website and video sharing website, YouTube.^[2]

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 hotel in Las Vegas using a timed series of eruptions. Later Eepybird videos featured "self-actuating" soda jets 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.^[3]

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 physics teacher Lee Marek, and others. MythBusters later created what is believed to be the highest soda jet 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.^[4] Water molecules strongly attract each other, linking together to form a tight connection around each bubble of 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 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 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.^[5] 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 jet effect.^[6] 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 eruption, by their claim, affirming the nucleation-site theory. This was further supported when rock salt was used as an effective substitute for Mentos.^[6] The experiment was also repeated in an episode of Numb3rs.^[7]

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.^[8] This theory was also tested on MythBusters: They used a pig's stomach as a human analogue with tubing that allowed for the insertion of the Coke and Mentos. The resulting expansion was not enough to rupture the stomach. Also, in testing the cause of the eruption, one of the hosts drank the mixture and ended up spitting it out.^[6]

Notes

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