• Question: Why if you put Mentos In Coca-Cola does it fizz up in simple words

    Asked by SuperCFay to Colin, John, Kevin, Shikha, Triona on 12 Nov 2014.
    • Photo: Tríona O'Connell

      Tríona O'Connell answered on 12 Nov 2014:

      This happens for the same reason that fizzy drinks fizz up badly and go everywhere when you pour them into a mug.
      The mug and the mentos don’t have a smooth surface when you look very closely. If you looked closely and compared it to a glass, they’d be very rough and the glass would appear very smooth. The rough surface has jaggy points for bubbles to form on (technical term – nucleation points) so lots of bubbles form and break off. The smooth surface has very few jagged points for bubbles to form on.
      When you put loads of mentos into coke, there’s suddenly lots of jagged points on which to form bubbles, so bubbles form, lots of them, suddenly, messilly. Bubbles!

    • Photo: Shikha Sharma

      Shikha Sharma answered on 12 Nov 2014:

      Hi SuperCFay,
      Coke has bubbles because of carbon dioxide that is pumped in to the bottle at the factory. This means that there is a lot of carbon dioxide gas just waiting to escape from the liquid in the form of bubbles. When you drop any sort of object into a bottle of coke, bubbles form on the surface of the object. This is known as nucleation. Surface of a Mentos is covered by lots and lots of tiny craters. These tiny pits create a larger surface area and essentially provide many more nucleation sites. Coatings of Mentos contain gum arabic, a surfactant that further reduces surface tension in the liquid. So, when you drop Mentos in coke a lot of bubbles are formed. When all of this gas is released it forces the liquid up and come out of the bottle in a huge whizzing fountain of sticky soft drink.

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