This summer we started working with the boys to film their own videos to raise money for their Xbox 360. Here is one of the experiments that they wanted to do. It involves a hard candy called mentos and the carbonated soda coke-a-cola. color scheme . After seeing the reaction that these two ingredients had in several episodes on Youtube, the boys decided to try their own experiment using Diet Coke. Amir describes the experiment…

First: I took the mentos out of the package.

Second:We made the funnel out of papper  .We put the mentos into the funnel.

Third:Then I put the funnel into the coke, and dropped the candy in the bottle.

Then the coke busted out of the bottle.It looked like a volcano.

And we talked about it.

Why it Happens… (via newscientist.com)

“Water molecules like to be next to other water molecules, so basically anything that you drop into the soda that disrupts the network of water molecules can act as a growth site for bubbles, And if you have rough candy with a high ratio of surface area to volume, then there’s more places for the bubbles to go.”

Low surface tension also helps bubbles grow quickly. Measurements showed that the surface tension in water containing the sweetener aspartame is lower than in sugary water, explaining why Diet Coke creates more dramatic fountains than sugary Coke.

Another factor is that the coatings of Mentos contain gum arabic, a surfactant that further reduces surface tension in the liquid. Rough-surfaced mints without the surfactant did not create such large fountains.

Mentos are also fairly dense and sink rapidly, quickly creating bubbles that seed further bubbles as they rise. Crushed Mentos that fell more slowly created puny fountains that only travelled about 30 centimetres.

4 replies on “Mentos + Coke”

  1. Hey guys!

    It’s great that you are doing science experiments on your website! I love science too.

    You know what’s really interesting to me? That scientists still don’t know exactly why Mentos and Diet Coke react that way! Maybe one day you guys can discover why…

    The next step as scientist is to find out if Mentos have the same reactions with other soft drinks. Would it do the same with Mountain Dew? Or Diet Pepsi?

    Good work fellas!

    Love,
    Uncle Mo

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