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Cola And Mentos: Cool Stuff

I bet you’ve all heard of the delicious drink cola. It has so much sugar that your mum or dad has probably banned you from drinking it. But what if I was to say that you could put all that sugar to good use? Yep. It’s a bit messy, but it’s worth it!

Get a big bottle of cola (Diet Coke works best) and put it in an area of your garden where nothing will get damaged. Then, get a pack of mentos (and a few extra, just in case) and open the lid of your cola. Carefully, place the mentos inside and run at least a metre away. Watch as the cola explodes up into the air, but prepare to clean up aftarwards!

Now we’ve had our fun, time for the science bit. A carbonated beverage is packed full of dissolved carbon dioxide gas, which forms bonds with water. While the soda is in the bottle, the gas is kept in solution by the bottle’s pressurized conditions. When you pour some soda into a glass, some gas escapes and forms foam, but most stays trapped by the surface tension of the water. But all those gas bubbles want to escape, making it no wonder that soda makes you burp!

To create bubbles, the carbon dioxide needs to interact with itself, which means that the carbon dioxide’s bonds with water in the Diet Coke must be broken. A Mentos candy can help with this. Although the candy may look smooth, if you looked at it under a microscope you’d see tiny bumps coating its entire surface. This rough surface allows the bonds between the carbon dioxide gas and the water to more easily break, helping to create carbon dioxide bubbles and cause the classic eruption. The speed at which the Mentos falls through the soda can affect how large the eruption is, and this can be tested by comparing whole with crushed Mentos, the latter of which are less dense.


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