• Question: why does a coke bottle explode when you drop in a mint (:

    Asked by imeeeldaaaa to Hywel, Joseph, Patience, Poonam, Rachael on 17 Jun 2010 in Categories: . This question was also asked by missberney.
    • Photo: Joseph Cook

      Joseph Cook answered on 16 Jun 2010:

      I think this is not because of a chemical reaction, but because the mints have a rough surface and contain a surfactant that reduces the surface tension of the coke, both of which allow the bubbles in the coke to fizz up more quickly. So it’s similar to when you open a bottle of coke and is fizzes over, but the effect is amplified.

    • Photo: Poonam Kaushik

      Poonam Kaushik answered on 16 Jun 2010:

      the caffeine, potassium benzoate, aspartame, and CO2 gas contained in the Diet Coke, in combination with the gelatin and gum arabic ingredients of the Mentos, all contribute to the jet effect.[10] In addition, MythBusters theorized that the physical structure of the Mentos is the most significant cause of the eruption due to nucleation. Mythbusters reported that when flavored Mentos with a smooth waxy coating were tested in carbonated drink there was hardly a reaction, whereas standard Mentos added to carbonated drink formed an energetic eruption, affirming the nucleation-site theory. According to 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.

      I was unaware about this! thanx for letting me know as well I took this from WIki. From this source
      http://en.wikipedia.org/wiki/Diet_Coke_and_Mentos_eruption

    • Photo: Dr Hywel Jones

      Dr Hywel Jones answered on 17 Jun 2010:

      It normally has to be a mento because these have a particularly porous surface. This means that for the same size sweet (compared to say a polo) there is far more surface area. The gas in the coke (carbon dioxide) likes to escape from the coke when it sees a nice rough surface (the mento surface) and when it does this it forms a bubble of gas in the coke. This then floats to the surface and is the fizz you see on the top of fizzy drinks. This is called nucleation.
      You can see nucleation if there is some dirt on the bottom of a glass (try it with lemonade as it is transparent) and the bubbles will form on this small patches of dirt or dust and you will see a stream of bubbles.
      Some beer glass manufacturers use this effect to keep a head on pints of larger by deliberately forming nucleation points on the bottom of pint glasses so that the gas is constantly released, always forming a new head on the beer.

Comments