Soda geyser

I told Billy about the soda/mentos geyser video I saw on the Adventures in Living blog. He, of course, thought it was very cool and came home with some cheap diet soda and mentos.

I went to
Steven Spangler's site for the details. He has a fantastic site, full of science experiments.


This activity is probably best done outside in the middle of an abandoned field, or better yet, on a huge lawn.

Carefully open the bottle of soda. Position the bottle on the ground so that it will not tip over.

Unwrap the whole roll of Mentos. The goal is to drop all of the Mentos into the bottle of soda at the same time (which is trickier than it looks). One method for doing this is to roll a piece of paper into a tube just big enough to hold the loose Mentos. You'll want to be able to position the tube directly over the mouth of the bottle so that all of the candies drop into the bottle at the same time.

As you probably know, soda pop is basically sugar (or diet sweetener), flavoring, water and preservatives. The thing that makes soda bubbly is invisible carbon dioxide gas, which is pumped into bottles at the bottling factory using tons of pressure. Until you open the bottle and pour a glass of soda, the gas mostly stays suspended in the liquid and cannot expand to form more bubbles, which gases naturally do. But there's more...

If you shake the bottle and then open it, the gas is released from the protective hold of the water molecules and escapes with a whoosh, taking some of the soda along with it. What other ways can you cause the gas to escape? Just drop something into a glass of soda and notice how bubbles immediately form on the surface of the object. For example, adding salt to soda causes it to foam up because thousands of little bubbles form on the surface of each grain of salt.

The reason why Mentos work so well is two fold: Tiny pits on the surface of the candy and the weight of the candy. Each Mentos candy has thousands of tiny pits all over the surface. These tiny pits are called nucleation sites - perfect places for carbon dioxide bubbles to form. As soon as the Mentos hit the soda, bubbles form all over the surface of the candy. Couple this with the fact that the Mentos candies are heavy and sink to the bottom of the bottle and you've got a double-whammy. When all this gas is released, it literally pushes all of the liquid up and out of the bottle in an incredible soda blast.

We just did it a few minutes ago in our yard and it went about 10'-11'!!! LOL!!! It was great! (We're easily amused) :-)

Try it and let us know how it goes!