How Does It Work?
Speaking to large crowds of buyers in New York, Steve Spangler shared a condensed history of the original geyser experiment. “Science teachers have been doing this experiment for years and years, but the original method used Wintergreen Lifesavers. When the manufacturer of the candies changed the diameter making them larger than the opening of the 2-liter bottle, teachers went looking for a substitute.” Steve explained that MENTOS candy did the trick, but dropping them into the bottle and getting away before being covered in soda was difficult. “That’s why we created the Geyser Tube. Now you get a perfect drop every time without getting drenched.”
- You’ll need a 2-liter bottle of diet soda (diet doesn’t make a sticky mess) and an outdoor location for your geyser. Select a flat surface to place the bottle.
- Pull the double-action trigger pin to the “out” position and drop 2-5 MENTOS candies into the Geyser Tube. Once the candies are in the tube, push the trigger pin to the “in” position, locking the candies in the tube. You can also add the MENTOS into the tube by untwisting the red cap atop the tube, and dropping the candies in that way.
- Once the candies are settles into the tube, unscrew the 2-liter soda bottle’s cap and replace it with your Geyser Tube.
- Warn everyone to stand back. Countdown… 3-2-1… and pull the trigger. The MENTOS will drop and the soda will go flying into the air!
- Pour out the remaining soda and take a look at the MENTOS. You can see where the soda has eaten away at the surface of the candy. No need to waste the candy… they still taste great.
Take the Taste Test
You’ll notice that there is still some soda left in the bottom of the bottle. Twist off the Geyser Tube and taste the soda. Beside tasting minty fresh, you’ll probably notice that all of the bubbles of carbon dioxide are gone. The soda is flat. Very interesting!
The Science Behind the Fizz
What made the soda shoot up so much higher? You already know why the soda erupts (if you forgot, re-read the explanation part of the previous experiment called The Original MENTOS Geyser). Look closely at the cap on top of the Geyser Tube. Do you notice the small hole in the top? That’s the secret! The smaller hole caused the soda to build up more pressure and the result was a 20 to 30 foot soda geyser.
You may have also noticed the clear plastic sleeve that slides back and forth on the Geyser Tube. When you pull the pin, the sleeve drops down to cover the two holes at the bottom of the Geyser Tube where the pin used to be. Without the sleeve, lots of soda shoots out from the two holes and keeps the geyser from going higher. Steve Spangler worked on many ways to keep the soda from shooting out of the holes and the sleeve method is the one he liked the best (and so did the attorneys who filed the patent for the Geyser Tube).
The Geyser Tube® is a registered trademark of Steve Spangler, Inc. All right reserved.
Science Fair Connection:
Setting off a Mentos Geyser isn’t, by itself, a science fair project. There are some very easy ways to make experimenting with geysers a great science fair project, though. The key to creating an awesome Mentos Geyser themed science fair project is isolating a variable. A variable is a component of the experiment that changes and, hopefully, alters the experiment. Some examples of possible variables with the Mentos Geyser include:
- Try different brands or types of soda and find a way to measure which erupts the highest.
- Test different numbers of Mentos to find the number of Mentos that creates the tallest geyser.
- Find out what temperature is best for geyser eruptions.
These are just examples of variations that you can try to turn the Mentos Geyser Tube into a science fair project. Remember, you have to keep all other factors the same. If you’re testing different brands of soda, make sure the number of Mentos you use is always the same and that the sodas are kept at the same temperature.