Coca Cola + Mentos Prank
Diet Coke and Mentos Eruption (also known as a Mentos eruption or a coke geyser) is a reaction of Diet Coke and mint Mentos candies, a two-liter bottle of Diet Coke (other carbonated beverages may be used instead; Diet Coke is preferred because it tends to react better) and dropping some Mentos into the bottle, usually around four. This causes the Diet Coke to foam at a rapid rate and spew into the air. Mint-flavored Mentos are used, as fruit-flavored Mentos have a smooth coating which slows the reaction. Because of the nature of this physical reaction and the easy availability of the ingredients, the eruption is a popular subject for Internet videos, and has also appeared in non-Internet sources.
A variation of this experiment consists of making the bottle rocket up by closing the cap shortly after Mentos is inserted and then slamming the bottle into the ground cap first. The explosion will generate a reaction like a rocket.In a 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 jet effect. In addition, the MythBusters theorized that the physical structure of the Mentos is the most significant cause of the eruption due to nucleation. 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. According to the MythBusters, the surface of the mint Mentos is littered with many small holes, allowing CO2 bubbles to form very rapidly and in great quantity, in turn causing the jet of foam. This was further supported when rock salt was used as an effective substitute for Mentos.