Adventures in Ethics and Science

We continue discussions with the elder Free-Ride offspring about potential projects for the spring science fair.

Elder offspring: Maybe I could do an experiment with Mentos and soda.

Dr. Free-Ride: You mean that one where you use Mentos to create a fountain of soda?

Dr. Free-Ride’s better half: That’s not an experiment. It’s a cliché.

Dr. Free-Ride: Like sticking battery-leads into a dill pickle.

Dr. Free-Ride’s better half: But less illuminating.

Elder offspring: Well, I’ve never put Mentos in soda.

Dr. Free-Ride: But from what you’ve read, you have a pretty good idea what’s going to happen, right? For a science fair project, it might be nice if you end up learning something you didn’t know before.

Elder offspring: Maybe good science fair projects get surprising results.

Dr. Free-Ride: Unfortunately, it can be hard to plan a project to get surprising results.

Younger offspring: If you expect them, you won’t be surprised.

Dr. Free-Ride: So, is there something new you could learn from the Mentos and soda?

Elder offspring: I could add Mentos to different kinds of soda and see which one makes the biggest mess.

Dr. Free-Ride: Is there maybe a different observable we could track than potential for mess-making?

Younger offspring: What if it was outside?

Dr. Free-Ride: Harumph.

Elder offspring: Hmm. I could try to figure out why mixing Mentos and soda creates a fountain of soda.

Dr. Free-Ride: Now you’re talking. How could you do that?

Elder offspring: Hmm. I read that putting salt in soda kind of does something similar.

Younger offspring: Is it like vinegar and baking soda?

Elder offspring: No! Well … I don’t think so.

Dr. Free-Ride: Soda and Mentos both have their ingredients listed on the label.

Elder offspring: If we can get those different ingredients, we could try testing them to see which ones make the fountain happen.

Dr. Free-Ride: That’s true. You might also need to learn a little bit about the behavior of solutions, like carbonated water.

Younger offspring: Carbonated water?

Dr. Free-Ride: That’s water with carbon dioxide dissolved in it. That’s what makes soda fizzy.

Elder offspring: Can we get water with carbon dioxide dissolved in it but nothing else?

Dr. Free-Ride: We can make water with carbon dioxide dissolved in it but nothing else. We can use the seltzer bottle and a CO2 cartridge.

Younger offspring: Cool.

Dr. Free-Ride: And, if you find out more about solutions, you might think about other things that could make a difference besides which ingredients get mixed with which.

Younger offspring: Like what?

Dr. Free-Ride: Well, have you noticed that when a bottle of soda has been opened, putting it in the fridge helps keep it from going flat so quickly?

Elder offspring: No. But you hardly ever let us have soda.

Dr. Free-Ride: For experimentation, I could make an exception.


  1. #1 Rick Pikul
    September 26, 2008

    I think you may have just sold EO on the idea with a single sentence.

  2. #2 chall
    September 26, 2008

    ohh… I want to see that experiment. I get so curious what makes thing bubble and go “fountain” 🙂

    When I taught 13yr olds chemistry we had a quick test with comparing two cans of diet coke and regular coke. And a huge bucket with water. The question was if either, both or none would float…..

    Yes, the diet one does. No, the regular doesn’t. It was such a fun thing to show and then we had a discussion about density and sugar and “what on earth is asparatam”.

    Please keep us updated on the Science project!

  3. #3 Donalbain
    September 26, 2008

    The mythbusters did this exact experiment. It is pretty cool, but be aware that it probably won’t be unique.

  4. #4 Tony Jeremiah
    September 26, 2008

    Hmm. I could try to figure out why mixing Mentos and soda creates a fountain of soda.

    The Mythbusters Mentos/Diet Coke episode and their nucleation hypothesis might be useful info.

  5. #5 Alan Kellogg
    September 27, 2008

    One Mentos tablet.
    Eight ounces of soda water.

    How far would this power a toy car?

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