Wrap the paper around the pack of Mentos to make a tube. Use masking tape to tape the tube closed. Remove the pack of Mentos from the tube.
Close off one end of the tube by cutting a little circle or square of paper and taping it to one end of the tube. Put the open end of your tube of Mentos on the card and place it directly over the opening of the soda bottle. When you are ready, remove the card and let all the Mentos drop into the soda at once and quickly move out of the way. The carbon dioxide molecules attach to the surfaces of the Mentos like they did in the cup of soda.
All those Mentos in a lot of soda make a lot of bubbles that rise to the surface and push the soda out in a big woosh! Mentos and Diet Coke! In the Diet Coke bottle the Mentos candy provides a rough surface that allows the bonds between the carbon dioxide gas and water to break more easily, helping to create carbon dioxide bubbles.
As the Mentos candy sinks in the bottle, the candy causes the production of more and more carbon dioxide bubbles, and the rising bubbles react with carbon dioxide that is still dissolved in the soda to cause more carbon dioxide to be freed and create even more bubbles, resulting in the eruption.
Because Mentos candies are rather dense, they sink rapidly through the liquid, causing a fast, large eruption. The crushed Mentos candies, however, are not as dense as the whole ones, which causes them to sink more slowly, creating a relatively small cola fountain, which should also leave more liquid in the bottle than the larger eruption with whole Mentos candies did.
Cleanup Hose off any part of a building that was splashed with Diet Coke. If you try this project with regular Coke, the eruption should still happen but its sugary content may make cleaning more difficult. This activity brought to you in partnership with Science Buddies. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Go Paperless with Digital. Build a Cooler. Get smart. Sign up for our email newsletter.
Sign Up. Why the difference? Two reasons could account for this difference. First, in Video 3 it was observed that Mentos addition causes a slight decrease in pH in a process that takes several minutes. Another reason could be that the pores on the Mentos can only support bubble growth in solutions that have CO 2 concentrations that exceed a critical value.
However, once the CO 2 concentration drops below the critical value, the CO 2 can no longer degas. Therefore, because boiling removes all dissolved CO 2 but Mentos addition does not, the former causes a larger pH shift than the latter. The rainbow of colors observed when boiling club soda to which universal indicator was added was a real treat for me to observe.
What a simple experiment: add the indicator to club soda, boil the resulting mixture, and watch the rainbow slowly unfold over time! Most sodas do not display such a drastic color change, given that they have acidic additives such as citric acid, instead of the potassium bicarbonate and potassium citrate in club soda. These simple demonstrations can be used to talk about a variety of concepts: chemical vs.
As CO 2 in the atmosphere increases, the amount of CO 2 dissolved in the ocean increases Equation 1 gets driven to the left. This in turn causes Equations 2 and 3 to be driven to the right, increasing the acidity of the oceans.
Indeed, the pH of the oceans has been observed to drop in an effect known as ocean acidification. As you can imagine there is much concern over the impact that ocean acidification has on marine life. As you can see in Video 2, I used bromocresol green and club soda to get a green-to-blue color change during the Mentos-induced degassing of soda. I also used a home carbonatioin system and bromocresol green to observe a green-to-yellow color change upon pumping CO 2 into water with a home carbonation system.
In Video 3, universal indicator was used to cause a red-to-orange color change. Please drop me a line in the comments if you try this demonstration on your own — or learn how to produce other color changes!
Kuntzleman, T. Baur, J. Coffey, T. Diet Coke and Mentos: What is really behind this physical reaction? Gardner, D. Educator , 19, — Huber, C. Quantifying the Soda Geyser. Sims, T. Diet Coke and Coke Zero react better with Mentos than regular Coke does because of the absence of sugar. A lack of sugar makes the soda mixture less viscous, given the presence of sweeteners, like aspartame, lowering the surface tension even more than usual. This in turns means that the carbon dioxide gas is more rapidly released.
The nucleation process is also faster, leading to higher gas pressure. We can see how much better Diet Coke and Coke Zero react with Mentos just by looking at the experiment we showed earlier: both of these sugar-free sodas produced fountains that exceeded 2. So, in a nutshell or, more aptly, a Mentos shell , soda mixtures with more sugar in them are more viscous, making their reactions less powerful.
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