Soda Bottle Volcano

roll of mint Mentos (type of candy)
clear 2-liter bottle of Coke (diet works better)

Go outside to an area where you have a lot of room. This experiment is messy!

Open the bottle of soda carefully. Position the bottle on the ground, so that it will not tip over.

*Diet soda works better than regular soda. Plus, diet doesn’t leave a sticky mess.

Unwrap the roll of Mentos. The goal is to drop the Mentos into the bottle at the same time, which is very tricky. One method is to roll a piece of paper into a tube just big enough to hold the loose Mentos. Put a card under the roll and on top of the bottle top, so you can pull the card and the candies will just drop in at once.

Drop all of the Mentos into the bottle at the same time and then move out of the way just as quick as you can.

Watch the eruption!

Why does this happen? Water molecules attract to other, linking together to form a tight mesh around each bubble of carbon dioxide gas in the soda. When you drop the Mentos in the soda, the gelatin and gum arabic from the dissolving candy break the surface tension. Each Mentos candy has thousands of pits on the surface. These tiny pits are called nucleation sites, perfect places for the carbon dioxide bubbles to form. As soon as you drop the Mentos in the soda, bubbles form all over the surface of the candy. Couple this with the fact that the candies are heavy and sink to the bottom of the bottle and you’re just asking for an explosion. When all this gas is released, it literally pushes all the liquid up and out of the bottle in an amazing blast.