Mentos Drink Prank – The Hoax!
This "time-delayed" practical joke is a great idea – until some experimenting shows it to be a flop.
The prank made the rounds online: “Create an Exploding Drink!” It uses the well known combo of Mentos® candy and diet soda that will create an eruption of foam. The time-delay part comes from hiding a some Mentos in an ice cube. You serve a friend a “refreshing” soda (loaded with a prepared ice cube) and the candy is exposed to the soda when the ice melts around it. The soda then supposedly erupts out of the glass as a result. Great idea… but it’s likely a scientific wannabe.
Mentos® is a registered trademark of Perfetti Van Melle Benelux B.V.
- Mentos® candy (original mint flavor)
- Diet soda
- Ice cube tray
- Drinking glasses
- Shallow container
- Adult supervision
If you’ve never had the thrill of dropping six or seven Mentos into a two-liter bottle of room temperature diet soda, now’s your time. Oh, what the heck… even if you’ve done it a thousand times, there’s nothing like that foaming geyser. Enjoy the rush but do it outside only!
With the reaction you just saw in mind, discover what you get with the prank idea. Barely cover the bottom of the ice tray with a layer of water and freeze it.
Lay one or two Mentos on the thin layer of ice in the tray. Add enough water to just cover the candies and freeze the tray overnight.
(This is gonna be great!) Pour some soda into a glass and drop in a couple of loaded ice cubes along with some plain ones. (Try to act normally even though you know the secret.) Wait for it… wait for it… OK, it’s a bust.
A few bubbles might be visible on the surface of the soda but it certainly is not a foaming mess! What gives?
How Does It Work
Think about the original eruption in Step 1. Look closely at a piece of Mentos candy. You can see thousands of very tiny pits (nucleation sites) all over its surface. Those tiny pits are one of the keys to all of the soda geysers you’ll ever make from now on. The pits are ideal for releasing huge amounts of carbon dioxide (CO2) bubbles very rapidly over and over.
Another reason is that Mentos are heavy for their size and quickly sink to the bottom of the bottle. That means in order to get out, all that gas has to push all that liquid out of its way. It makes for a great fountain of liquid and foam! Researchers suggest that several of the ingredients in the soda may also help in the formation and release of the gas bubbles, too. Some act like a “soap” and increase bubble production greatly. By the way, after an eruption, the soda has a faint, minty flavor and the Mentos are still very chewy. Enjoy!
Take It Further
Now, what about the failed prank? It’s likely that the loss of all those nucleation sites on the surface of a Mentos candy is to blame for the failure. How did they disappear, you ask? The surface of the candy dissolved just enough in the water before it froze to cause the pits to vanish. The surface was as smooth as a… well, it was really smooth and there were no pits for the CO2 to collect in huge quantities. Devise some tests to reach your own conclusion about why there was no foaming.
- You need a control. In a shallow container to catch any overflow, pour some soda into a glass, add four ice cubes, and drop in two Mentos candies. Record your observations.
- Repeat the test with everything the same except, this time, dip each candy in water first and then dry them with a paper towel. Record your observations.
- Repeat the test with everything the same except, this time, dip each candy in water first and then dry them with a hair dryer. Record your observations.
- Repeat the test with everything the same except, this time, use one ice cube with two Mentos frozen in it in one glass and two plain Mentos taken from the freezer in another glass. Make sure freezer-time for the candies and the cubes is the same and use the same freezer. Record your observations.
No doubt you can devise your own tests to reveal the cause for the lack of foaming with ice-covered Mentos. Your results will be useful as long as all the tests are the same except for the one variable being tested.
Science Fair Connection
Actually, the tests suggested above are a pretty good start on your next science fair project.
This is a pretty safe experiment but it can be messy, so be ready with the cleanup supplies. Using tongs to handle straight-from-the-freezer ice cubes and candy is a good idea. It will also reduce heating caused by handling them with your hands.