Diet Coke and Mentos eruption

A 2-litre (0.44 imp gal; 0.53 US gal) bottle of Diet Coke just after Mentos were dropped into it
From left to right: action of five Mentos candies (per bottle) with Perrier, classic Coke, Sprite and Diet Coke

A Diet Coke and Mentos eruption (alternately Diet Coke and Mentos geyser or Mentos eruption) is a reaction between the carbonated beverage Diet Coke and Mentos mints that causes the beverage to spray out of its container.[1][2] The gas released by the candies creates an eruption that pushes most of the liquid up and out of the bottle.[3] Lee Marek and "Marek's Kid Scientists" were the first to demonstrate the experiment on television in 1999.[4] Steve Spangler's televised demonstration of the eruption in 2005 went viral on YouTube,[5][6][7] launching a chain of several other Diet Coke and Mentos experiment viral videos.[8]

History

In the 1980s, Wint-O-Green Life Savers were used to create soda geysers. The tubes of candies were threaded onto a pipe cleaner and dropped into the soft drink to create a geyser. At the end of the 1990s the manufacturer of Wintergreen Lifesavers increased the size of the mints and they no longer fit in the mouth of soda bottles. Science teachers found that Mint Mentos candies had the same effect when dropped into a bottle of any carbonated soft drink.[3]

Lee Marek and "Marek's Kid Scientists" performed the Diet Coke and Mentos experiment on the Late Show with David Letterman in 1999.[2][4][9] In March 2002, Steve Spangler, a science educator, did the demonstration on KUSA-TV, an NBC affiliate, in Denver, Colorado.[10] The Mentos Geyser Experiment became an internet sensation in September 2005. The experiment became a subject of the television show Mythbusters in 2006.[9][11] Spangler signed a licensing agreement with Perfetti Van Melle, the maker of Mentos, after inventing an apparatus aimed to make it easier to drop the Mentos into the bottle and produce a large soda geyser.[12] Amazing Toys, Spangler's toy company, released the Geyser Tube toys in February 2007.[13] In October 2010, a Guinness World Record of 2,865 simultaneous geysers was set at an event organized by Perfetti Van Melle at the SM Mall of Asia Complex, in Manila, Philippines.[14] This record was afterwards beaten in November 2014 by another event organized by Perfetti Van Melle and Chupa Chups in Leon, Guanajuato, Mexico where 4,334 Mentos and soda fountains were set off simultaneously.[15]

Cause

The eruption is caused by a physical reaction, rather than any chemical reaction. The addition of the Mentos leads to the rapid nucleation of carbon dioxide gas bubbles precipitating out of solution.[16] Gasses, in general, are more soluble in liquids at elevated pressures. Carbonated sodas contain elevated levels of carbon dioxide under pressure. The solution becomes supersaturated with carbon dioxide when the bottle is opened, and the pressure is released. Under these conditions, carbon dioxide begins to precipitate from solution, forming gas bubbles. Normally, this process is relatively slow, because the activation energy for this process is high. The activation energy for a process like bubble nucleation depends on where the bubble forms. It is highest for bubbles that form in the liquid itself (homogeneous nucleation), and lower if the bubble forms on some other surface (heterogeneous nucleation). When the pressure is released from a soda bottle, the bubbles tend to form on the sides of the bottle. But because they are smooth and clean, the activation energy is still relatively high, and the process is slow. The addition of other nucleation sites provides an alternate pathway for the reaction to occur with lower activation energy, much like a catalyst. For instance dropping grains of salt or sand into the solution lowers the activation energy, and increases the rate of carbon dioxide precipitation. The physical characteristics of Mentos (surface roughness, easy dissolution into the liquid, etc.) have the effect of drastically reducing the activation energy for carbon dioxide bubble formation, so that the nucleation rate becomes exceedingly high. This formation of gaseous carbon dioxide within the water, which due to hydrogen bonding and its high surface tension wants to maintain a connected matrix of molecules, causes the water to foam, ultimately generating the "jet"—or "geyser"—or eruption-like nature of the effusion.[11][3][14][17] The foaming is aided by the presence of chemicals like potassium benzoate and aspartame in Diet Coke, and gelatin and gum arabic in the Mentos candy, all which influence the nature of water's surface tension and degree to which it can foam.[9][11][14]

The nucleation reaction can start with any heterogeneous surface, such as rock salt, but Mentos have been found to work better than most.[3][11][14] Tonya Coffey, a physicist at Appalachian State University, found that the aspartame in diet drinks lowers the surface tension in the water and causes a bigger reaction, but that caffeine does not accelerate the process. The geyser reaction will still work even using sugared drinks, but diet is commonly used both for the sake of a larger geyser as well as to avoid having to clean up a sugary soda mess.[16][18]

See also

References

  1. ↑ Hazel Muir (2008-06-15). "Science of Mentos-Diet Coke Explosions Explained". Retrieved 2014-09-30.
  2. 1 2 Michelle Bova (2007-02-19). "How Things Work: Mentos in Diet Coke". Retrieved 2014-09-30.
  3. 1 2 3 4 Spangler, Steve (2010). Naked Eggs and Flying Potatoes. Greenleaf Book Group Press.
  4. 1 2 Suzanne Baker (2014-05-23). "Naperville students integral to classic TV bits, but will the fun continue?". Retrieved 2014-09-30.
  5. ↑ Clayton Neuman (20 April 2007). "The TIME 100 — Are They Worthy?". TIME. Retrieved 22 June 2014.
  6. ↑ Steve Spangler Science (26 June 2006). "Orchestrated Chaos: A Mentos Tribute to Eepybird.com". Retrieved 24 July 2014.
  7. ↑ SpanglerScienceTV (6 June 2012). "Original Mentos Diet Coke Geyser". YouTube. Retrieved 24 July 2014.
  8. ↑ "Diet Coke and Mentos, Near Death". 239Media. 2 August 2006. Retrieved 8 November 2014.
  9. 1 2 3 Tonya Shea Coffey. "Diet Coke and Mentos: What is really behind this physical reaction?" (PDF). Retrieved 2014-09-30.
  10. ↑ "The Original Mentos Geyser Video". Retrieved 2014-09-30.
  11. 1 2 3 4 "Mythbusters: Diet Coke and Mentos MiniMyth". Discovery Channel.
  12. ↑ Al Lewis (2006-11-07). "Mentos-soda mix a mint for scientist". Retrieved 2014-09-30.
  13. ↑ Greg Sandoval (2007-02-13). "Toying with the Diet Coke and Mentos experiment". Retrieved 2014-09-30.
  14. 1 2 3 4 Daven Hiskey. "Why Do Mentos and Diet Coke React?". Retrieved 2014-09-30.
  15. ↑ "Most Mentos and soda fountains". Guinness World Records. Retrieved 2015-02-05.
  16. 1 2 Muir, Hazel (June 12, 2008). "Science of Mentos-Diet Coke explosions explained". New Scientist. Retrieved 2009-09-20.
  17. ↑ "Mentos and Soda". MythBusters. Season 4. Episode 14. August 9, 2006. Discovery Channel.
  18. ↑ Coffey, Tonya Shea (June 2008). "Diet Coke and Mentos: What is really behind this physical reaction?". American Journal of Physics. 76 (6): 551–557. doi:10.1119/1.2888546.

Further reading

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