Mentos in Pop!

One of the most fun science activity to do with pop is to make it erupt.

You will need:

2-L bottle of pop (diet cola works great), 8-12 Mentos candies, Plastic tube to hold 8-12 Mentos

Now try this:

1. Place 8-12 Mentos candies into a plastic tube.

2. DO THIS OUTSIDE. Place 2-L bottle of pop on the ground and carefully remove the top.

3. Carefully (but quickly) place the plastic tube on top of the 2-L bottle of pop and deliver the Mentos.

4. Run really fast or stay and get sprayed by the pop.

What is happening?

The pop is a water solution that contains a gas called carbon dioxide. When you open the bottle of pop you can see the evidence of this gas as tiny bubbles going to the surface. The gas is put into water under pressure, opening the bottle lowers the pressure, thus releases some of the gas. When the Mentos candies are dropped into the pop the surface tension of the water is lowered, reducing the strength to contain the gas. Mentos also provides this gas small areas (called nucleation sites) on the candy to escape out of the water solution. This gas attracts other gases in the pop solution causing a great big eruption. What's surprising about this eruption is that it is not a chemical reaction, just a physical change because the gas was already there in the pop.