Boom baby boom!

The Mentos effect

To explain the foamy geyser that results from Mentos and Coke being combined you need to think of Physics.

Sodas like Coke contain compressed carbon dioxide. It's the gradual expansion and release of this pressurized gas in the form of bubbles that makes the fizz in carbonated drinks. It's the surface tension of the liquid - the strong attraction that bonds its water molecules together, that prevents the gas from escaping all at once.

When Mentos are added, that surface tension is disrupted by the additives in the candy - gelatin and gum arabic, and the outside surfaces of the Mentos provide encourages the rapid formation of bubbles. When you drop Mentos into a carbonated beverage, it causes the sudden release of pressurized gas which blows up out of the narrow neck of the Coke bottle giving a fantastic fountain effect.

So drop some Mentos candies into a bottle of Coke, shake it up if you dare and MOVE away from it.

Oh, and do this outside. And guess what Ms S substituted for the Coke?

Look at the picture to see if you guessed correctly.