When I worked for Disney Cruise Line one of the experiments we used to do with the children was the Diet Coke and Mentos experiment; it was part of a show called Super Sloppy Science: Gases and Goos. It was a particularly messy show that would require at least an hour clean up.
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I would highly recommend that if you do this (which I hope you do) with your little ones that you do it OUTSIDE!
You Will Need:
- Diet coke*
- Geyser tube – you can get them amazon.co.uk for a few pounds.
*You can use any fizzy drink, but diet coke is sugar free so it isn’t sticky.
Make sure that you don’t let all the fizz out of the diet coke when you open it, other wise this won’t work very well. Flat coke is a definite no no for this.
Screw the geyser tube onto the top of the coke and make sure that the button is in.
Fill the tube up with Mentos and put the lid on tightly.
Then holding the bottle steady pull the button out and watch the amazing diet coke geyser erupt. Trust me when I say don’t stand over it, otherwise you will feel the full effect of it.
YC and one of her friends did this in the local park after school and we had quite a few people stop to watch what we are doing. This really is a lot of fun.
The Science Behind It
I had to learn the basic science behind for the show, but there is a whole Myth Busters TV show based on learning what causes this to happen.
Basically, the surface of the Mentos are covered in tiny craters, which increase the surface area. Each little crater provides a site for CO2 bubbles to form; this is called nucleation. Lots of CO2 bubbles form very quickly and as the Mentos sink it cause the geyser effect that you see. The coke and Mentos are so perfectly matched that is makes the soda want to give up its CO2 all at once, which is known as the cascade effect.
The Myth Buster team tested lots of different types of fizzy drinks and worked out that to make this work well you need CO2, Aspartame, Potassium Benzoate and Caffeine. Which are all thankfully found in Diet Coke – lucky us.
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