Thursday, 10 November 2011

Soda Fountain

This is a classic experiment, I think, judging from the numerous examples on the internet I have found of the same experiment conducted all over the world.

The basic ingredients are: mentos and soda.  Since I am a curious Mum, I wanted to see whether the experiment works with other minted sweets, such as Polo.  My initial hypothesis was that the chemical reaction (as you will see later) was caused by the mint flavouring, so it would not matter which type of mint was used. 

I knew it was going to be a messy experiment, so we did it in the back garden.  Sure enough, the mentos fountain was spectacular, even though it only lasted for 5 seconds.

You can see the experiment more clearly in the following video:

We then tried to do the same with Polo sweets.  It did NOT work.  So, my hypothesis was wrong. One good thing about being wrong is that we can go on to find out why we are wrong and then correct our erroneous belief/hypothesis.

After reading different articles and listening to the explanation provided in the video above, we figured out that the hollow space in the Polo sweet does not allow enough air bubbles to build up (compared to the surface area that each mentos sweet has), which in turn does not give enough pressure to push the soda out of the bottle.  Of course, I'm sure other factors such as the different chemicals used to make Polo sweets will affect its interaction with the chemicals in the soda, but we will leave this further investigation for when we actually concentrate on chemistry lessons and learn about the different elements.

Here is a good one that explains the science behind the experiment.  Once again, there is no straightforward, simple answer.  Different people have different theories about why the reaction happens.  That's the beauty of science, isn't it?  That there is always something new to learn.

This post is linked up to several blog hops, where you can visit to see what other homeschoolers have been busy with.


  1. Hmmm...I really wish we could be learning in your neck of the woods. You guys have so much fun! :)

  2. This is one of Steve Spangler's favorites and his has a pretty good explanation as well. I haven't been brave enough to try it yet. Thanks for the great visuals.

  3. We've done this numerous times in the past! Fun, messy stuff! Too bad it didn't last longer though, huh? (And it gets expensive doing bottle after bottle of soda! LOL)

  4. We've done this experiment a few times and it's always a lot of fun for the kids!

  5. This is a SUPER post. I love how you bring home the concept of 'mistakes' and how learning from them can be such a powerful lesson. Great job.


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