There’s nothing more fun than making a mess outdoors during summer’s lovely weather. So this month we are presenting a very contemporary experiment: the (in)famous Mentos and cola geyser.
You will need bottles of pop (diet cola is a great starting point) and plenty of mints (Mentos are standard).
Pop is fizzy because it has had carbon dioxide dissolved in it. This is just the same as dissolving salt in water (except it’s done by adding pressure to the liquid, rather than heat) – just as extra salt in your water will come out as grains that fall to the bottom, extra CO2 will come out of the pop as bubbles that rise to the top. The bubbles only need a place to form, and the millions of microscopic pits on the surface of – for example – a Mentos mint do the job very efficiently.
When you put a Mentos into the pop, the dissolved carbon dioxide will stop being dissolved and resume being a gas rather quickly. As the bubbles rush upward, they’ll push liquid out of their way – and out of the bottle in a huge geyser. Kids love this experiment so much because of the huge geyser and the mess it creates and it’s also a good source of experimentation. Start with Mentos and 2L of diet soda (diet has a bit more carbonation), and then try changing the dynamics of the experiment one ingredient at a time. For example, try other candies, or even stones, or have fun changing the bottle size, number of mints, temperature, type of pop, etc. You can even make nozzles for your bottle to shape your geyser.
Just remember that this is most definitely an outside experiment – and one to stand back from. There should be adult supervision at all times.
If you love to experiment and find really great combinations, share it with our community on Facebook (http://www.facebook.com/DiscoveryCentre). There’s always a conversation on the go, and we welcome everyone to join in! You can also take videos of your experiment and upload those too.