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.