In the video, Mentos candies are added to diet soda and there is huge eruption. The goal of the video is to help students think of experiments that they can perform themselves to try to figure out why this happens. The video explores questions like, "does it have to be diet cola?", "does it have to be Mentos?", "do other things besides candy work?" and so on. This is an especially interesting experiment because it is a lot of fun.
So ask your student to think of some questions he/she would like to explore. Go buy the soda (a place like Wal-Mart sells really cheap soda in 2-liter bottles) and the candy and then have fun performing your own experiments.
PLEASE NOTE - IF YOU ARE USING FULL 2-LITER BOTTLES OF SODA, DO NOT DO THIS INDOORS. The geyser can rise 10 to 12 feet into the air and will easily hit the ceiling in most homes. It can make a huge mess. This is definitely an outdoor experiment.
The obvious question to ask at some point is what, exactly, happens when you put an innocent piece of candy in a bottle of soda? Why does it create a geyser like this?
The answer is that no one knows for sure. However, by performing your experiments, you can notice certain patterns.
First, you may notice that diet soda works better than sugar-sweetened soda. One reason -- diet soda is lighter than sugar-sweetened soda. Diet sweeteners are lighter than sugar. You can prove this easily by noticing that a bottle of diet soda will float in water, while a bottle of sugar-sweetened soda will sink.
The release of all the foam so fast is probably do to the surface roughness of the Mentos. Try salt as one of the things you drop into soda. You may notice that it works just as well as the candy.
There may also be some kind of effect that occurs because chemicals in the Mentos change the surface tension of the water in the soda. If you want to explore this idea, try putting a little soap in the soda and see what happens.