Volcano Model Eruption

Margaret Morgan: My name is Margaret Morgan, I am a science educator in Pinellas County, Florida and now I am going to cover another way to make a volcano erupt using Diet Coke and Mentos. So how does this work? How is a volcano formed when you combine Diet Coke and Mentos. Well, it has to with for one thing with the Carbon Dioxide that is in the Diet Coke. There is Carbon Dioxide dissolved in Diet Coke and that Carbon Dioxide would rather be in gas form than dissolved in Diet Coke and when you add Mentos to diet coke. The Mentos provide a surface on which the Carbon Dioxide can form bubbles, so that it go into gas form. Now the reason that Mentos provide such a good surface is that the Mentos actually have a rough surface. There are actually are microscopic bumps on the surface of the Mentos and what that means is that the Mentos have a lot of surface area. So they provide a great place for a Carbon Dioxide to form bubbles. Now another reason that Carbon Dioxide has a tough time going back in the gas form and getting out of the coke is surface tension. The Carbon Dioxide has trouble breaking the surface tension of the coke, but when you add Mentos to the coke, when the Mentos dissolves, they increase the concentration of sugar in the coke and not actually decreases the surface tension of the coke. So the Carbon Dioxide escapes more easily and the result of these two forces coupled is an explosion. This actually only works with regular Mentos, the regular mint flavored ones. The fruit flavored ones actually have a wax coating on them that makes this not work as well. We have already built our bottle of volcano around different bottles, so that we could do -- make our volcano using vinegar and baking soda but if you were doing it this way initially you would want to build your volcano around your Diet Coke bottle.

Now to make my volcano erupt I am going to add Mentos to this bottle of Diet Coke. This is an eruption, it's still going. Okay, of course it is always a good idea to have lots of towels and paper towels around to contain the mess factor when you are doing this. It is probably also a good idea to do it outside. Of course the bigger bottle of Diet Coke you use the higher its going to spray and the more Mentos you add, the bigger of an explosion you are going to get. Really the trick is to add as many Mentos as you can as fast as possible. But as you can see it's kind of messy. So just be prepared and Diet Coke of course is going to be less sticky than regular coke. So that's an important factor to keep in mind. I am Margaret Morgan, science educator, thank you for watching the how to make volcano video.


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