variables in mentos and coke experiment

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Diet Coke and Mentos Soda Geyser

The Diet Coke and Mentos soda geyser, also known as the soda and candy fountain or volcano, is a physical reaction between candy and carbon dioxide that instantaneously releases the gas so it shoots into the air. There is a lot of science behind this deceptively simple project! Here are instructions for performing the original project, tips for getting the tallest eruption, options for material substitutions, and a look at how the Diet Coke and Mentos geyser works.

All you need is a packet of Mentos candies and a 2-liter bottle of Diet Coke:

• Roll of Mentos candies
• 2-liter bottle of Diet Coke

Make sure the candy is fresh and the bottle of soda is unopened. Freshness matters!

You also need a way of delivering the candies into the soda. One method is just dropping the column from your hand, but rolling them into a paper or index card tube is more reliable. Stacking them into a test tube is another option.

Substitutions

While Mentos and Diet Coke work best, you have other options:

• Any carbonated beverage
• Any candy that stacks neatly into a column
• Coins, shot, or other small items that fit through the bottle opening
• Sand or salt instead of candy (which work quite well)

In general, diet carbonated beverages produce higher fountains than sugary ones. Also, they don’t produce a sticky mess. Uncarbonated beverages, like juice or water, do not work at all. Objects with smooth, flat surfaces (like coins) do not work nearly as well as other options.

How to Make the Diet Coke and Mentos Soda Geyser Erupt

The project is messy. You might want to step outdoors.

• Open the Mentos candies and stack them into a single column.
• Open the bottle of soda.
• Drop the column of candy into the bottle, all at once.

If you have more candy, you can repeat the eruption using the same bottle of soda. It won’t be quite as dramatic, but still works.

Tips for Getting the Biggest Eruption

• Diet Coke or other diet colas outperform any other drinks. There are a lot of potential reasons for this, mainly involving the effects of aspartame, potassium benzoate, and other ingredients on the surface tension and foaming capacity of the beverage. The worst carbonated beverages for this project are carbonated water and sparkling alcoholic drinks.
• The blue Mentos candies work better than other flavors. The fruity Mentos are reportedly the worst flavor. Freshly unwrapped candies are best. Old candy is not very effective, probably because humidity changes the candy surface.
• A 2-liter plastic bottle works better than any smaller bottle, whether it is plastic or glass.
• You get a better eruption at high altitude or low atmospheric pressure compared with sea level or other high pressure situation.
• Warm soda produces a higher fountain than cold soda.

How the Diet Coke and Mentos Experiment Works

The Diet Coke and Mentos eruption is a physical process more than a chemical reaction. The candy surface has many tiny imperfections and cavities, each only a micron or so in size. When you drop the Mentos into the soda there are numerous minute air bubbles stuck onto them. These little bubbles act as nucleation sites for rapid de-gassing of the soda:

CO 2 (aq) → CO 2 (g)

Because the nucleation sites lower the activation energy for bubble formation, you can say they catalyze the reaction.

The candies are dense enough that they sink to the bottom of the soda bottle, interacting with dissolved carbon dioxide as they fall. As carbon dioxide bubbles form, the gas is lighter than the liquid and the bubbles rise. As they rise, they expand. The pressure of the gas results in a quick release of pressure, making a geyser out of the soda. Ingredients in the partially-dissolved candy help the bubbles keep their shape and form a foam as the liquid ejects from the bottle.

Numerous investigations into why diet soda (especially cola) works better than sweetened soda or why Mentos works better than other candies answer some questions, but not all of them. The ingredients in the soda make a difference. However, which ones enhance bubble formation and which suppress it are unclear. The chemical composition of the candies likely contributes to bubble formation, but it’s really their surface structure that matters the most.

Turn the Science Project Into an Experiment

Performing the Diet Coke and Mentos project is easy, but turning the project into an experiment is also simple. Just find a variable under your control, predict the outcome from changing it, conduct an experiment that tests this hypothesis , and then analyze your results and see if your prediction was correct. Here are some ideas of variables you can explore:

• Is there an optimal number of candies for the best eruption?
• Compare different types of carbonated beverages. Do you think, for example, that Coke Zero performs as well as Diet Coke? Do other brands of diet cola perform as well?
• Explore the effect of soda temperature on fountain formation. If you see a difference, comparing chilled and warm soda, can you explain it ?
• Are there any candies that work as well as Mentos? In general, is there a way of predicting whether or not a particular kind of candy produces an eruption?
• What effect do you expect, if you add a bit of bubble solution or dishwashing liquid to the soda before adding the candy?
• Design different “candy delivery” systems. What are the pros and cons of each of them?
• Can you make a nozzle that reduces the diameter of the bottle? If so, what effect does this have on the height of the eruption?

Fun Facts About the Diet Coke and Mentos Project

• The original soda and candy fountain project, circa 1910, used Wint-O-Green Lifesaver candies (which as also great for the “spark in the dark” triboluminescence project ). However, the company changed the candy diameter in the 1990s and it no longer fits into most bottles.
• Scientists estimate the eruption releases between 2.4 and 14 million bubbles per liter of Diet Coke. Regular Coke produces a lot less bubbles.
• A single Mentos candy contains 50,000 to 300,000 nucleation sites, although the reaction does not utilize every one of them.
• Coffey, Tonya Shea (2008). “Diet Coke and Mentos: What is really behind this physical reaction?”. American Journal of Physics . 76 (6): 551–557. doi: 10.1119/1.2888546
• Kuntzleman, Thomas S.; Imhoff, Amanda M. (2021). “How Many Bubbles Are in the Foam Produced during the Candy-Cola Soda Geyser?”. Journal of Chemical Education . 98 (12): 3915–3920. doi: 10.1021/acs.jchemed.1c01001
• Kuntzleman, Thomas S.; Annis, Jezrielle; Anderson, Hazel; Kenney, Joshua B.; Doctor, Ninad (2020). “Kinetic Modeling of and Effect of Candy Additives on the Candy–Cola Soda Geyser: Experiments for Elementary School Science through Physical Chemistry”. Journal of Chemical Education . 97 (1): 283–288. doi: 10.1021/acs.jchemed.9b00796
• Kuntzleman, Thomas S.; Johnson, Ryan (2020). “Probing the Mechanism of Bubble Nucleation in and the Effect of Atmospheric Pressure on the Candy–Cola Soda Geyser”. Journal of Chemical Education . 97 (4): 980–985. doi: 10.1021/acs.jchemed.9b01177

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Mentos and Diet Coke Experiment

How to turn a bottle of soda and a roll of mentos into an exploding soda geyser.

Print this Experiment

It’s been called the “vinegar and baking soda” reaction for a new generation. While science teachers have been dropping candies and mints into 2-liter bottles of soda for years to release all of the dissolved carbon dioxide, the Mentos and Diet Coke reaction became world-famous in 2005. Fueled by hundreds of blogs and popular online sharing sites like youtube, this once obscure reaction became an Internet sensation. Once you get past the initial gee-whiz factor, there’s some amazing science behind a carbonated beverage and a chewy mint.

DOWNLOAD THE FULL EXPERIMENT

This full version of this experiment appears in Steve Spangler’s book called Naked Eggs and Flying Potatoes – Unforgettable Experiments That Make Science Fun

Experiment Videos

Here's What You'll Need

A roll or box of mentos chewy mints (stick with the standard mint flavor for now), 2-liter bottle of diet soda (either diet or regular soda will work for this experiment, but diet soda is not sticky when you’re cleaning it up, and it will usually create a bigger blast), sheet of paper to roll into a tube, steve spangler’s geyser tube toy (optional . . . but highly recommended), let's try it.

This activity is probably best done outside in the middle of an abandoned field or on a huge lawn.

Carefully open the bottle of diet soda. Again, the choice of diet over regular soda is purely a preference based on the fact that erupting regular soda becomes a sticky mess to clean up because it contains sugar. Diet soda uses artificial sweeteners instead of sugar, and consequently, it’s not sticky. Later on in the experiment, you’ll be invited to compare the geyser power of diet versus regular soda, but for now we’ll start with a 2-liter bottle of diet soda.

Position the bottle on the ground so that it will not tip over.

Let’s start with seven Mentos for our first attempt. The goal is to drop all seven Mentos into the bottle of soda at the same time (which is trickier than you might think). One method for doing this is to roll a piece of paper into a tube just big enough to hold the loose Mentos. Other methods include using a large plastic test tube to hold the Mentos or using my Geyser Tube toy invention, which was created to solve this very problem. Assuming that you’re using the paper tube method, you’ll want to load the seven Mentos into the tube, cover the bottom of the tube with your finger, and position the tube directly over the mouth of the bottle. When you pull your finger out of the way, all seven Mentos should fall into the bottle at the same time.

Enough waiting . . . this anticipation is killing me. 3-2-1 drop the Mentos!

This final step is very important . . . run away! But don’t forget to look back at the amazing eruption of soda.

If spectators were watching your exploits, someone is bound to yell out, “Do it again!” and that’s exactly what you’re going to do.

How Does It Work

Why do Mentos turn ordinary bottles of diet soda into geysers of fun? The answer is a little more complicated than you might think. Let’s start with the soda . . .

Soda pop is made of sugar or artificial sweetener, flavoring, water, and preservatives. The thing that makes soda bubbly is invisible carbon dioxide (CO 2 ), which is pumped into bottles at the bottling factory using lots of pressure. If you shake a bottle or can of soda, some of the gas comes out of the solution and the bubbles cling to the inside walls of the container (thanks to tiny pits and imperfections on the inside surface of the bottle called nucleation sites ). When you open the container, the bubbles quickly rise to the top pushing the liquid out of the way. In other words, the liquid sprays everywhere.

DOWNLOAD THE FULL MENTOS AND DIET COKE EXPERIMENT

Is there another way for the CO 2 to escape? Try this. Drop an object like a raisin or a piece of uncooked pasta into a glass of soda and notice how bubbles immediately form on the surface of the object. These are CO 2 bubbles leaving the soda and attaching themselves to the object. For example, adding salt to soda causes it to foam up because thousands of little bubbles form on the surface of each grain of salt. This bubbling process is called nucleation , and the places where the bubbles form, whether on the sides of the can, on an object, or around a tiny grain of salt, are the nucleation sites.

Why are Mentos so Special? The reason why Mentos work so well is twofold—tiny pits on the surface of the mint, and the weight of the Mentos itself. Each Mentos mint has thousands of tiny pits all over the surface. These tiny pits act as nucleation sites—perfect places for CO 2 bubbles to form. As soon as the Mentos hit the soda, bubbles form all over the surfaces of the candies and then quickly rise to the surface of the liquid. Couple this with the fact that the Mentos candies are heavy and sink to the bottom of the bottle and you’ve got a double whammy. The gas released by the Mentos literally pushes all of the liquid up and out of the bottle in an incredible soda blast.

Measuring the Height of the Geyser To make any of these tests meaningful, you need to find a way to measure the height of the eruption. A friend or parent with a video camera is a great way to watch and document the results of your experiment, but you’ll also need some specific measurements or data. Try placing the soda bottle next to the wall of a brick building (after getting permission from the building’s owner). Measure the height of the geyser by counting the number of bricks that are wet once the geyser stops. If you want a more specific measurement, use chalk to mark off 1-foot increments on the brick wall before you drop the Mentos into the bottle of soda. Make comparisons, create a chart with your data, and draw some conclusions. Be sure to thank the building’s owner and to hose off the wall of the building when you are finished!

Measuring the Volume of the Geyser If you want to examine the volume of the geyser instead of the height, make note of the volume of a full bottle of soda before you drop the Mentos into it. (Okay, it’s a trick question because a 2-liter bottle of soda holds . . . 2 liters!) Once the geyser stops, pour out the remaining contents of the bottle and measure how much liquid is left. You could use a beaker or a graduated cylinder to measure the remaining liquid in milliliters. Remember that 1 liter is equivalent to 1000 mL. Subtract the remaining amount of liquid from the original volume of the bottle to calculate the volume of the geyser. Then make comparisons, create a chart with your data, and draw some conclusions.

How Many Mentos Work Best? This has to be the number one question everyone asks about this experiment. What is the best number of Mentos to use to make the highest-shooting geyser? This is a great topic for a science project—you’ll need lots of soda and Mentos, and a few friends to help record all of the data.

Be sure that the soda bottles are all the same brand and type. It’s also important that all of the test bottles are stored in the same place so that the liquid in each bottle is the same temperature.

Line up a row of ten 2-liter bottles against a brick wall (see “Measuring the Height of the Geyser”). Each bottle will receive a different number of Mentos. Drop one Mentos into the first bottle and record the height by counting the wet bricks (or set up your own scale behind each soda bottle). Drop two Mentos into the second bottle, and so on until you’ve completed all ten bottles.

Of course, this could go on forever, but you’ll start to see a trend in your data that shows the maximum height of the geyser for a certain number of Mentos. Many soda geyser-ologists believe that seven Mentos produce the highest-shooting geyser. Using any more than seven Mentos is just a waste, according to these soda-soaked science enthusiasts. What do your results reveal about the effect of the number of Mentos on the height of the geyser?

The Brand Test You guessed it . . . it’s time to put your favorite soda to the test. Does one brand produce higher-flying geysers? How does generic soda stack up against the big name brands? If you’re doing a science fair project, your initial question might be, “What is the effect of the brand of soda on the height of the geyser?”

Use your data from the previous test to determine the standard number of Mentos to use for this test. The only variable you’ll change in this test is the brand of soda while everything else remains the same (the number of Mentos and the amount of soda). Again, make sure all of the soda is at the same temperature because temperature plays an important role in the reaction. The brand of soda is the only thing that changes (the variable). Just think . . . your results could help determine the next Mentos Geyser craze!

The Temperature Test What is the effect of temperature on the height of the geyser? Does warm soda shoot up higher than cold soda? The key is to keep every launch fair and to make sure the only variable is the temperature of the soda. You’ll need a thermometer to record the temperature of the soda just before you launch it.

To enforce the fairness factor, you must stick with one brand of soda for the entire test. Let’s use Diet Coke in this example. You’ll want to purchase three bottles of Diet Coke and two rolls of Mentos. You’re going to set up three tests—warm soda, room temperature soda, and cold soda. Place one bottle of Diet Coke in the refrigerator and let it sit overnight. Place the second bottle in a place where it can reach room temperature overnight. There are two safe ways to warm the other bottle of soda. The simplest method is to let the unopened bottle sit in the sun for several hours. You can also place the bottle of unopened soda in a bucket of warm water. Never use a stove or microwave to heat a bottle of soda.

It’s time to return to your launching site. Check to make sure your measuring scale is in place (counting bricks or using an alternative scale against the wall). Let’s start with the bottle of cold Diet Coke. Open the bottle and dip the thermometer down into the soda. Record the temperature. Load seven Mentos into your paper roll and drop them into the soda. Immediately record the data for the cold soda test. Repeat the same procedure for the bottle of soda at room temperature and for the bottle of warm soda. It’s important to use the same number of Mentos for each test and to drop them the same way.

No matter which brand of soda you tested, the warm bottle probably produced the highest-shooting geyser. Warm soda tends to fizz much more than cold soda. Why? The answer lies in the solubility of gases in liquids. The warmer the liquid, the less gas can be dissolved in that liquid. The colder the liquid, the more gas can be dissolved in that liquid. This is because as the liquid is heated, the gas within that liquid is also heated, causing the gas molecules to move faster and faster. As the molecules move faster, they diffuse out of the liquid, leaving less gas dissolved in that liquid. In colder liquids the gas molecules move very slowly, causing them to diffuse out of the solution much more slowly. More gas tends to stay in solution when the liquid is cold. This is why at the bottling plant CO 2 is pumped into the cans or bottles when the fluid is just above freezing—around 35 degrees Fahrenheit. This low temperature allows the maximum amount of CO 2 to dissolve in the soda, keeping the carbonation levels as high as possible.

Take It Further

Simply dropping Mentos into a bottle of soda to make a geyser isn’t really science—it’s just a fun trick to do in the backyard. The real learning takes place when you start to change one variable at a time to see how it affects the performance of the geyser.

PURCHASE Steve Spangler Original Mentos Geyser Tube on Amazon

The Big Blast After completing all of these tests, you’ve become somewhat of a Mentos Geyser expert who has the research to support the answer to the question, “How can you make the highest-shooting Mentos geyser?” Each test isolated an independent variable, and combining all of the information you discovered into one launch is a great way to wrap up your science fair project. For example, based on your individual test results, you might have arrived at this recipe for the best Mentos Geyser:

• Use a bottle of Diet Coke
• Make sure the soda is at least 85 degree Fahrenheit
• Drop seven Mentos into the soda all at the same time

By using the scientific method and some critical thinking skills, you’ve successfully turned a great gee-whiz science trick into a research-based science fair project.

Science Fair Connection

You might ask yourself, “Can I use the Mentos Geyser for my science fair project?” The answer is YES, but you’ll need to learn how to turn a cool science activity into a real science experiment. The secret is to turn your attention away from the spraying soda and concentrate on setting up an experiment where you isolate a single variable and observe the results.

To get the best results in a science experiment, you need to standardize the test conditions as much as possible. The biggest challenge in the Mentos Geyser experiment is finding a consistent way to drop the Mentos into the soda every time. The original reason I invented the Geyser Tube toy was to find a way to standardize the actual drop of the Mentos. If you’re not using the Geyser Tube, make sure to come up with your own method for dropping the Mentos into the soda the same way each time.

Mentos Geyser History—From Obscurity to Instant Celebrity

As strange as it might sound, the Mentos Geyser never actually started out using Mentos chewy mints. This science demonstration was popular among chemistry teachers back in the 1980s using a roll of Wintergreen LifeSavers and a pipe cleaner. Teachers threaded the roll of Wintergreen LifeSavers onto a pipe cleaner as an easy way to drop all of the LifeSavers into the soda at the same time. Within seconds of dropping the candies into the soda, a huge geyser would erupt from the bottle.

However, by the end of the 1990s, the manufacturer of Wintergreen LifeSavers increased the size of the mints (no one was ever certain why this happened), making the diameter of the candy too large to fit into the mouth of the soda bottle. Science teachers started experimenting (as they like to do) with other candies and mints that would have the same effect when dropped into a bottle of soda. As luck would have it, the solution to the problem was within arm’s reach of the Wintergreen LifeSavers in the candy aisle—it was Mentos chewy mints.

Because Mentos mints didn’t have holes in the middle like LifeSavers, getting them into the bottle was tricky. Everyone found their own method of quickly dropping the Mentos into the soda. Some people fashioned a tube out of paper while others used a piece of plastic tubing to load the Mentos. At the time, my solution was to load the Mentos candies into something called a Baby Soda Bottle—a test tube–like container that held an entire roll of Mentos perfectly. Oddly enough, this container was actually a “pre-form” or 2-liter soda bottle before it was blown up into a big bottle. That’s why it’s called a Baby Soda Bottle. However, I must admit that even with the Baby Soda Bottle method, the results were not very consistent and it was challenging to get away from the bottle before it exploded. So, I solicited help from our creative team at Steve Spangler Science to come up with a Geyser Tube— a better, more consistent way to drop the Mentos into the bottle. Better yet, if we could trigger the drop of the Mentos from a distance, we wouldn’t get as wet.

The next few months were spent building trigger devices ranging from plastic tubes with sliding doors to magnets that held metal stoppers in place to an elaborate battery-operated switch that was triggered by a motion detector. We even played with ways of using the Geyser Tube to trigger multiple soda geysers in a method similar to a Rube Goldberg machine. But the bottom line was that we needed to find a way to standardize the drop of the Mentos.

As they say, the simplest design usually turns out to be the best and most elegant solution to the problem. The winning Geyser Tube design was a clear plastic tube with a special fitting that twisted onto any soda bottle. The trigger pin at the bottom of the tube prevented the Mentos from falling into the bottle until you pulled the string attached to the pin. The moment the pin was pulled, a slider ring resting above the pin fell into place and covered the holes where the trigger pin once was, and the Mentos dropped into the soda. But there was one added bonus . . . the restricted hole at the top of the plastic tube helped to build up more pressure in the bottle and launched the soda 30 feet into the air. Fortunately, the maker of Mentos (Perfetti Van Melle) also liked the design, and we launched the Mentos Geyser Tube toy at the New York Toy Fair in February 2007. The Geyser Tube toy is currently available in toy stores and mass-market retailers throughout the country thanks to our distributor, Be Amazing Toys!

The Mentos Geyser became one of my featured demonstrations both on television and during my live stage presentations. While I had performed variations of the Mentos Geyser experiment on television many times from 2001 to 2004, my performance of the demo in September of 2005 in the backyard of NBC affiliate KUSA-TV in Denver proved to be the tipping point as the demo went from relative obscurity to Internet sensation.

My cohost for the KUSA-TV science segment was the lovely Kim Christiansen. During the commercial break, I told Kim what was going to happen and reminded her to pull her hand out of the way of the erupting geyser and to run backward. Unfortunately, Kim got so caught up in the fun that she forgot to do both . . . and got soaked in Diet Coke on live television. To add insult to injury, she did it two more times, each time getting covered in more soda, until her once pink dress was more Coke-colored than pink.

KUSA-TV News posted that original video on their website along with my blog post titled, “News Anchor Gets Soaked!” Within a few weeks, links to the video and my blog entry numbered in the thousands. I also posted the video on a new online video sharing site called YouTube (YouTube was only 7 months old at the time), and as they say, the rest is history. Within the next 12 months, over 800 Mentos Geyser-related videos were posted on YouTube, making the demo one of the most popular pop-culture science experiments in recent history.

Million Dollar Question

You know the Mentos Geyser is a popular experiment when a producer from ABC’s Who Wants to Be a Millionaire calls for help writing a question. Here’s the question we came up with: In an experiment popularized online, what candy creates an explosive geyser when dropped into a 2-liter Diet Coke bottle?

A) Skittles B) Mint Mentos C) Atomic Fireballs D) Lemon Heads

The question was asked on a special College Week episode of Who Wants to Be a Millionaire. The participant got it right for $8,000, saying: “I saw it on TV and I bought Mentos and a 2-liter bottle of Diet Coke . . . so I’m going to go with Mentos. That’s my final answer.” The contestant ended up doing really well, going all the way to the $250,000 question, but he walked away with $125,000.

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Mentos and Coke Experiment: How-To Plus Free Worksheet

This explosive experiment teaches kids about physical reactions.

Adding Mentos candy to Coke is the stuff of legend. Every kid has heard the rumors about the explosive combination that results, but how many have actually tried it? While science teachers have been performing this experiment for years, it was first popularized in September of 2005 thanks to a viral video from Steve Spangler Science . The several-foot-high geyser that shoots from the soda bottle is a fun and awe-inspiring hands-on activity that any scientist in the making can perform. Be forewarned though: You’ll probably want to perform this experiment outside.

Read on to learn more about the Mentos and Coke experiment, and fill out the form on this page to grab your free recording sheet for the experiment.

How does the Mentos and Coke experiment work?

In this experiment, you drop Mentos mints into a 2-liter bottle of Coke. Make sure your bottle of soda is on a flat surface in a location where it is OK to make a mess. You then load the Mentos into your paper roll or geyser tube . Once the Mentos are dropped into the soda, they sink to the bottom, which causes the gas to expand and pushes the soda out of the bottle. This creates an exploding geyser effect.

What does the Mentos and Coke experiment teach?

Although you can’t see it, dissolved carbon dioxide is the invisible substance that makes soda bubbly and fizzy. As long as the soda remains in the bottle, the gas is kept in place through the pressurized conditions. When you shake a bottle of soda, some of that gas is released and the bubbles stick to nucleation sites or tiny defects on the inside of the container. If you open the shaken bottle, the bubbles will rapidly rise and push the liquid up and out of the bottle.

Aside from shaking the soda, another way to help the carbon dioxide escape is to drop an object into the bottle. Mentos are the perfect objects, since each candy has many little pits on its surface that serve as nucleation sites. Once the Mentos are dropped into the soda, the bubbles stick to those sites and quickly rise to the surface. The weight of the Mentos drives them to the bottom of the bottle. Then, the gas that is released by the Mentos forces the soda to shoot out of the bottle in a powerful geyser.

Is there a Mentos and Coke video?

This video shows how to do the Mentos and Coke experiment using just a few simple ingredients and supplies.

Materials Needed

To do the Mentos and Coke experiment, you will need:

• A roll or box of mint-flavored Mentos
• 2-liter bottle of Coca-Cola (aka Coke)
• Sheet of paper to roll into a tube OR pre-made geyser tube

Our free recording sheet is also helpful—fill out the form on this page to get it.

Mentos and Coke Experiment Steps

1. make a paper tube by taking a piece of paper and wrapping it around a roll of mentos, then taping it in place. pull the mentos out. alternatively, you can use a premade geyser tube available from amazon or other retailers..

2. If using a geyser tube, load the Mentos. If using a homemade paper roll, drop the Mentos into the roll while holding the bottom closed with your finger.

3. Placing a 2-liter bottle of Coke on a flat surface, remove the cap, and drop the Mentos into the open Coke bottle.

Grab our free Mentos and Coke experiment worksheet!

Fill out the form on this page to get your worksheet. The worksheet asks kids to guess the correct order of the steps in the experiment. Next, kids must make a prediction about what they think will happen. They can use the provided spaces to draw what happens before and after they add the Mentos. Did their predictions come true?

Additional Reflection Questions

• What happened when we added the Mentos to the Coke?
• What difference do you think the temperature of the Coke makes?
• What do you think would happen if we used different-flavored Mentos, like fruit?
• What do you think would happen if we used a different soda other than Coke?
• What do you think would happen if you use Diet Coke?

Can the Mentos and Coke experiment be used for a science fair?

Yes! If you want to do the Mentos and Coke experiment for a science fair, we recommend switching up some of the variables. For example: Does the temperature of the Coke matter? Does the brand of soda matter? Will generic soda produce the same results as the brand-name soda? What happens if you use fruit-flavored Mentos? What happens if you use Diet Coke instead of regular? Form a hypothesis about how changing the variables will impact the experiment. Good luck!

Looking for more experiment ideas? Check out our  big list of experiment ideas here.

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Have you ever noticed that when you put a straw in soda pop, the straw gets a lot of bubbles on it? Why does that happen? And will it happen if you put other stuff in soda pop?

    1. Very slowly and carefully, open a new bottle of colorless soda.

    2. Tilt the cup and slowly pour the soda down the inside of the cup to make as few bubbles as possible.  

3. Place a straw in the soda and look at the straw from the side.   

4.  Take the straw out of the soda and put a pipe cleaner in. Look from the side to see if bubbles also form on the pipe cleaner. 

5. Now take the pipe cleaner out and place a Mento in the soda. Watch the Mento from the side to see what happens.

 What to expect

Bubbles will form on the straw and very quickly and completely cover the pipe cleaner.

What's happening in there?

Why do the bubbles form on the different things you put in the soda?

The bubbles are made of a gas called carbon dioxide. The soda company puts carbon dioxide in the soda to make the soda fizzy.

Also, the things you put in the soda aren’t really as smooth as they look with just your eyes. If you could look at the straw, pipe cleaner, and Mento with a super-strong microscope you would see that they have tiny dents, scratches, and bumps on them. 

The carbon dioxide molecules collect on these places and form bubbles which rise to the surface.

Make a Mentos-and-Soda Fountain!

There is a pretty cool thing you can do with a bottle of soda pop and a packet of Mentos. Let’s try it!

First, make a tube for the Mentos.

1. Cut a piece of paper so that it is as wide as a roll of Mentos.

2. 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.

3. 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.

4. Open the pack of Mentos and place all of them in the tube.

Now, make a Mentos-and-soda fountain!

1. Slowly and carefully open a new bottle of Diet Coke.  

2. Place it on a flat area outside where it is OK to get wet with soda.

3. Put the open end of your tube of Mentos on the card and place it directly over the opening of the soda bottle.

4. 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.

Bubbles and soda will quickly shoot out of the bottle in a high fountain.

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!

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Science Sunday: Diet Coke and Mentos

• Aoife Ryle & Mark Dixon
• April 27, 2020

Materials to Collect

• Unopened diet coke
• Mentos (any flavor)
• An outdoor space
• Old clothes 
• Place your new bottle of diet coke in a place you don’t mind soaking in diet coke. 
• Take the cap off the bottle and drop some mentos in. 
• Get out of the way!

What is the Science? 

That foaming, fizzing, bubbling craziness erupting from the bottle is the result of a physical reaction. This means that the molecules involved are moved or rearranged, but they are not changed. 

So how does this molecular rearranging happen? Diet soda (and all carbonated beverages) are saturated with carbon dioxide gas. That’s what gives it that signature fizzy taste. If all of that dissolved carbon dioxide was able to bunch up together, it would erupt from the bottle in bubbles and foam. This is where the mentos come in. Mentos candies are covered in tiny bumps and ridges that give the carbon dioxide a surface to collect and group together on. As those carbon dioxide molecules group together, they are forced up and out of the small bottle opening very quickly. 

Create an Experiment

Now it’s time for the fun part – designing your own experiment! In order to do this, have your scientist(s) think of one component to change. This is the experiment’s variable. The variable could be something like the number of mentos dropped into the bottle, the flavor of diet soda, the size of the bottle, or the temperature of the soda. It doesn’t matter what your variable is, it just has to be one concrete thing that you can change. 

Everything else in your experiment should stay the same. So for example, if I wanted to study how changing the number of mentos dropped into the diet coke affects the explosion, I would make sure that the size of the soda bottle stayed the same, the temperature of the soda stayed the same, the flavor mentos stayed the same, etc.

Finally, once you have figured out your variable (the thing changing) and figured out a way to keep everything else the same, you just have to figure out how to collect data. You need a way to track how changing your variable affects your outcome. Make sure your scientist(s) help figure this step out! For this experiment, you might choose tracking the height of your diet coke explosion or measuring how much diet coke is left in the bottle after. 

When you’re all done, we would love to see your results! Share your data, your graphs, or your experiment videos with us using #ScienceAtPlay.

Aoife Ryle is a STEM Educator at the Connecticut Science Center. In addition to working with school groups, she works with our Teen Program, Overnights department, and shoots weekly science segments for WFSB. She has a degree in Bioengineering from the University of Maine and has a personal interest in the life sciences and engineering which makes bioengineering a perfect crossover.

Mark Dixon is a meteorologist on WFSB Channel 3 Eyewitness News and a host of the weekly Science Sunday segments with the Connecticut Science Center. He has been nominated for several Emmy awards for weather anchoring and has won awards from the Connecticut Associated Press Broadcaster’s Association and the American Meteorological society.

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Mentos and Coke Experiment – How to Do It! [Full Guide]

Have you ever taken a can of soda, shook it up, and given it to your friend?

What happens?

Well, it’s probably not pretty. And you may not have a friend for a day or two until they forgive you.

But making soda explode is fun. And there is a way to make it really go boom if you have a few pennies and a bit of time on your hands.

Note – be sure to only try this experiment with a responsible adult!

It really only takes a few minutes to setup the mentos and coke volcano experiment. And it’s a great way to learn about chemical reactions.

It’s also a lot less work than your classic paper mache volcano. So, if you want some quick and easy fun, get some paper towels because we’re about to make a sweet mess.

What Will I Need For The Mentos And Coke Volcano?

There really aren’t that many supplies you need to make a mentos and coke volcano.

But here’s the list:

An outdoor area with no ceiling or roof

One roll of Mentos candies

A two-liter bottle of diet soda (diet soda makes for a much better reaction, but you can use regular soda if you like. It just won’t be nearly as awesome.)

A tube the width of the Mentos . It needs to be wide enough to use as loader for the Mentos

An index card (picture below)

The Mentos And Coke Volcano Experiment

Now it’s time to actually run the experiment, but first, we need to make a hypothesis.

The Hypothesis

The scientific method is an important way scientists make observations and come to conclusions.

Part of the scientific method is making a prediction called a hypothesis .

Write down what you think will happen when placing the Mentos in the soda bottles.

Do a little bit of research about the ingredients of Mentos and soda.

This will help you make an informed guess as to what will happen.

Now You Test The Hypothesis

In an experiment, you have two groups: an experimental group, and a control group.

Open the soda bottle, set it down and write down what you observe about it.

This will count as your control group. It’s what happens when you put nothing in the soda.

Now take the Mentos in your tube loader.

Put the index card on top of the tube loader and turn the tube upside down.

The candy should not fall out.

Be ready. The reaction happens fast, so don’t have your face over the bottle.

Place the index card and candies over the mouth of the bottle. Make sure the candies are in line with the mouth of the bottle.

You want the candies going in the bottle and not falling over the side.

Now remove the index card and let candies fall in and step away from the Mentos and coke volcano.

Write down what happened when you dropped the Mentos in the coke.

Did what you hypothesize happen? Compare your notes on the experiment to the control group.

Let us know what you observed in your science experiment!

FREQUENTLY ASKED QUESTION

1. can i use any type of mentos candy for the experiment.

Yes, you can use any type of Mentos candy for the experiment. The most commonly used Mentos candies are the original mint-flavored ones, but you can also use fruit-flavored or other varieties. The key factor is the rough surface of the Mentos candy, which helps to create nucleation sites for the carbon dioxide bubbles in the Coke. This happens because Coke contains dissolved carbon dioxide gas.

2. What happens if I use diet Coke instead of regular Coke?

If you use cold diet Coke instead of regular Coke in the Mentos experiment, you can still expect an explosive reaction. However, the reaction may not be as vigorous as with regular Coke. Diet Coke contains artificial sweeteners like aspartame, which may slightly affect the reaction. Nonetheless, the combination of Mentos and diet Coke can still produce a notable geyser, so it’s worth giving it a try. SO it will be the mentos geyser experiment.

3. Is the Mentos and Coke experiment suitable for children to try at home?

The Coke and Mentos experiment can be a fun and engaging activity for children to try at home. However, ensuring proper adult supervision and following safety precautions is important. Conducting the mentos experiment outdoors or in a well-ventilated area is recommended to avoid any potential mess or accidental spills. Additionally, remind children not to consume the Coke or Mentos mixture, as it is unsafe for ingestion. By taking these precautions, the Coke and Mentos experiment can provide children an educational and entertaining experience.

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June 14, 2012

Spurting Science: Erupting Diet Coke with Mentos

A carbonated challenge from Science Buddies

By Science Buddies

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Key concepts Chemistry Physics Materials science Carbonation Physical reactions Explosions Introduction Have you ever seen the Diet Coke and Mentos experiment that is all over the Internet and wondered what makes the reaction work? You might think that there is some ingredient in a Mentos candy that causes a chemical reaction with the soda pop, like the way baking soda reacts with vinegar. But the amazing eruption that takes place when Mentos are dropped into Diet Coke or other brands of diet soda pop is not a chemical reaction at all! Instead it is a physical reaction. That means that all of the pieces of the reaction are there, but that they are simply rearranged. It also means changing some factors may cause a larger or smaller physical reaction to take place. Background A carbonated beverage is packed full of dissolved carbon dioxide gas, which forms bonds with water. While the soda is in the bottle, the gas is kept in solution by the bottle's pressurized conditions. When you pour some soda into a glass, some gas escapes and forms foam, but most stays trapped by the surface tension of the water. But all those gas bubbles want to escape, making it no wonder that soda makes you burp! To create bubbles, the carbon dioxide needs to interact with itself, which means that the carbon dioxide's bonds with water in the Diet Coke must be broken. A Mentos candy can help with this. Although the candy may look smooth, if you looked at it under a microscope you'd see tiny bumps coating its entire surface. This rough surface allows the bonds between the carbon dioxide gas and the water to more easily break, helping to create carbon dioxide bubbles and cause the classic eruption. The speed at which the Mentos falls through the soda can affect how large the eruption is, and this can be tested by comparing whole with crushed Mentos, the latter of which are less dense. Materials •    Wax paper •    Cutting board •    Knife •    One roll of Mentos (at least eight candies) •    Two index cards •    Tape •    Two two-liter bottles of Diet Coke •    An outdoor area at least two meters from buildings •    Eye protection (safety goggles or glasses) •    Video camera with either a tripod or a helper to take the images (optional) Preparation •    Place a piece of wax paper on top of the cutting board. On the wax paper, carefully use a knife to crush and cut four Mentos candies into many small pieces. An adult may help you cut up the candies. What does the inside of the candies look like? •    Make a Mentos cartridge to hold the candies for you before you drop them into the Diet Coke bottle by rolling an index card into a tube, slightly larger than the diameter of a Mentos candy. Tape the tube together on the side. •    Be sure to wear eye protection when putting the candies into the cola! •    Wear clothes that you would not mind if they get splashed with a little soda pop—this activity can get a little messy! Procedure •    Place a Diet Coke bottle in an outdoor area, at least two meters from any buildings or anything hanging above the area, such as eaves, overhangs or wires. Make sure that the bottle is on a level surface and stably standing straight. Why do you think all of this is important? •    If you want to videotape the reactions, set up the video camera so that it has in its viewfinder the bottle and a height equivalent to at least the first story of a building. •    Carefully remove the cap from the bottle and place the flat index card on top, covering the hole. •    Add four whole Mentos candies to your cartridge, put on your eye protection, and start the video camera. •    Place your full cartridge on top of the flat index card. Line up where the opening of the bottle is with the opening of your cartridge. Quickly pull out the flat index card, releasing the Mentos candies into the bottle. Then step back without tipping the bottle over or disturbing the reaction. •    How quickly did the reaction start to happen, and how quickly did it stop? About how high did the eruption go? How much cola is left in the bottle? •    When the bottle stops spouting, stop recording. •    Remove the spent cola bottle and place a new full bottle in the same position, again making sure that it is level and stably standing straight. As with the first bottle, remove the cap and place the flat index card on top, covering the hole. •    Add your four crushed Mentos candies to your cartridge, pouring them in from the wax paper. Put on your eye protection and start the video camera. •    Like you did before, place your full cartridge on top of the flat index card, then line up where the opening of the bottle is with the opening of your cartridge. Quickly pull out the flat index card, releasing the crushed Mentos into the bottle, then step back without tipping the bottle over or disturbing the reaction. •    How quickly did the reaction start to happen, and how quickly did it stop? How high did the eruption appear to go? How much liquid is left in the bottle? Is it more or less than the amount that was left when you used whole candies? •    When the bottle stops spouting, stop recording. If you videotaped the reactions, you can watch your videos now. What do you notice from the videos? •    Which reaction went higher, the whole or the crushed Mentos? •    Extra : Find an exterior wall of a building with no windows and set a Diet Coke bottle at the base of the wall. Use a tape measure and blue painter's tape to mark off the height from the top of the bottle in meters. Then repeat this activity three times, with the bottle in front of the tape-marked wall, video taping it each time. When you review the recordings, use slow motion and pause the recording when the spout is at its maximum height. Using the tape marks in the background, estimate the height of the spout. Calculate the average height of the fountains for the whole and for the crushed Mentos . What is the difference in height of the eruptions? •    Extra: What other factors affect the size of the Mentos and Diet Coke eruption? You can try testing different kinds of carbonated beverages, different kinds of candies with different shapes and textures or using other things to start the reaction, like rock salt, pennies or dice. Which beverages, candies or other things cause the largest and smallest fountains? Why do you think this is? •    Extra: Do this activity again but instead of testing whole Mentos versus crushed, compare warm versus cold Diet Coke. Does temperature affect the eruption height? Observations and results Was the eruption higher when whole Mentos candies were used compared with crushed candies? Was less Diet Coke left in the bottle after the reaction with the whole candies compared with the crushed ones? 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. More to explore Physicists Explain Mentos–Soda Spray from Scientific American Science of Mentos–Diet Coke explosions explained from New Scientist The Science of Coke and Mentos from EepyBird.com Why do Mentos mints foam when you drop them into soda pop? from General Chemistry Online Coke® & Mentos®—Nucleation Goes Nuclear! from Science Buddies

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Why Do Mentos Explode in Coke?

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The chemical reactions involved in dropping mentos candies into a bottle of diet coke make quite the spectacle! Soda geysters, which can reach as high as ten meters, were a popular subject for viral videos in the early 2000's, but the science behind the spectacle remained a mystery until 2008.

Chemistry and Physics

Applications.

Many people speculated that the geyser was the result of an acid base reaction , given the low pH of soda. However, none of the ingredients in mentos are basic, and the experiment works to some degree with any type of soda and any type of candy.

Mentos candies are not as smooth as they appear to the naked eye. They are covered in bumpy craters, which increases the total surface area. A Mentos dropped into a bottle of soda acts as a surfactant , meaning it reduces the surface tension of the soda. Water molecules are polar and attracted to each other. Anything that breaks them apart allows for bubbles of carbon dioxide gas to form in the solution. A rougher candy surface translates to more places for bubbles to grow, or more nucleation sites . Surfactants are compounds that lower the surface tension (or interfacial tension) between two liquids or between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, and dispersants.

This is essentially speeding up the process that makes sodas fizzy. Bottled sodas are kept under pressure so that more carbon dioxide can be forced into solution. When the pressure is released, the carbon dioxide is forced out of solution and makes little gas bubbles. So, if you open a bottle of soda gently, you get a pleasant beverage. If you shake the can first, you disrupt the solution and get a face full of soda. And if you add a big enough surfactant, you get a geyser. It's the same chemistry, but a different magnitude.

The two biggest factors affecting the geyser are the roughness of the candy used and the rate at which it sinks to the bottom of the soda bottle. [1] Other factors that affect the growth rate or total number of carbon dioxide bubbles also changed the geyser's height, such as temperature and the original surface tension of the soda. Diet Coke makes a better spectacle than regular Coca-Cola because both aspartame and benzonatate (a preservative used in artificially sweetened drinks) lower surface tension more than sugar does.

Mixing mentos and soda makes a great science demonstration for students studying gases, thermodynamics, fluid dynamics, surface science, and the physics of explosions among other chemistry and physics concepts. [1]

Tonya Coffey, a professor at Appalachian State University, used the experiment to give her undergraduate physics class a real-world research experience as one of their laboratory assignments. The project was eventually published in the American Journal of Physics . Though the manuscript is behind a paywall, a presentation that Dr. Coffey made about the experience is available on the schools website. [2]

The force exerted by the soda stream can be harnessed to do work. One enterprising group made a mentos and diet coke-powered rocket. However, the practical applications of this reaction are limited by the sticky mess it makes.

The engineer explains that the yellow nose cap is full of mentos, while the body is full of pressurized diet coke. Watch the full video for a more detailed explanation. [3]

There is an urban legend that eating mentos while drinking soda could cause a person's stomach to burst. However, most of the carbonation is released from the soda as it is being drunk, so the pressure is lower and carbon dioxide is less likely to nucleate. Additionally, the stomach has a couple ways of expelling excess gases.

A mint-flavored mentos makes a geyser 5 meters high and a fruit-flavored mentos makes a geyser 2 meters high when the two candies are put into identical bottles of soda under identical experimental conditions. What is the most reasonable hypothesis to explain the difference?

• Coffey, T. (2008). Diet Coke and Mentos: What is really behind this physical reaction?. American Journal of Physics , 76,551 .
• Coffey, T. Diet Coke and Mentos . Retrieved from http://www.appstate.edu/~coffeyts/DietCokeandMentos.pdf
• Milleaccendini, Y. Youtube . Retrieved March 18, 2016, from https://www.youtube.com/watch?v=mb6neBVtvsE

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Science of Mentos-Diet Coke explosions explained

By Hazel Muir

12 June 2008

Scanning electron microscope images show the roughness of mint Mentos (top and bottom left) and fruit Mentos (top and bottom right), the scale bars representing lengths from 20 to 200 micrometres

(Image: T Coffey/Dewel Microscopy Facility/AAPT)

The startling reaction between Diet Coke and Mentos sweets, made famous in thousands of YouTube videos, finally has a scientific explanation. A study in the US has identified the prime factors that drive the fizzy plumes from Coke bottles: the roughness of the sweet and how fast it plummets to the bottle’s base.

“If you drop a pack of Mentos into a bottle of Diet Coke, you get this huge fountain of spray and Diet Coke foam coming out,” says Tonya Coffey , a physicist at Appalachian State University in Boone, North Carolina. “This was a good project for my students to study because there was still some mystery to it.”

When mint or fruit Mentos are dropped into a fresh bottle of Diet Coke, a jet of Coke whooshes out of the bottle’s mouth and can reach a height of 10 metres. Theories abound as to why this happens, with some bloggers speculating that it is an acid-base reaction because Coke is acidic.

Experiments in a 2006 edition of the Discovery Channel programme Mythbusters suggested the chemicals responsible for the reaction are gum arabic and gelatine in the sweets, and caffeine, potassium benzoate and aspartame in the Coke. But there have been no rigorous scientific studies of the reaction until now.

Fizzy liquids

To find out more, Coffey and a team of students tested the reactions between Diet Coke and fruit Mentos, mint Mentos, and various ingredients such as other mints, dish-washing detergent, table salt and sand. They also compared reactions using other fizzy liquids such as caffeine-free and sugary colas, as well as soda water and tonic water.

All the reactions took place in a bottle angled at 10° off vertical and the fountain trajectories were recorded on video. The team also investigated the total mass lost in the fountain and the influence of the sweet’s surface roughness.

The results showed that Diet Coke created the most spectacular explosions with either fruit or mint Mentos, the fountains travelling a horizontal distance of up to 7 metres.

But caffeine-free Diet Coke did just as well, suggesting that caffeine does not accelerate the reaction, at least at the normal levels in the drink.

Measurements of the pH of the Coke before and after the experiments showed that its acidity did not change, ruling out the idea that a simple acid-base reaction drives the fountains.

Instead, the vigour of the jets depends on various factors that affect the growth rate of carbon dioxide bubbles.

The rough, dimply surfaces of Mentos encourage bubble growth because they efficiently disrupt the polar attractions between water molecules, creating bubble growth sites.

Rough candy

“Water molecules like to be next to other water molecules, so basically anything that you drop into the soda that disrupts the network of water molecules can act as a growth site for bubbles,” Coffey told New Scientist . “And if you have rough candy with a high ratio of surface area to volume, then there’s more places for the bubbles to go.”

Low surface tension also helps bubbles grow quickly. Measurements showed that the surface tension in water containing the sweetener aspartame is lower than in sugary water, explaining why Diet Coke creates more dramatic fountains than sugary Coke.

Another factor is that the coatings of Mentos contain gum arabic, a surfactant that further reduces surface tension in the liquid. Rough-surfaced mints without the surfactant did not create such large fountains.

Mentos are also fairly dense and sink rapidly, quickly creating bubbles that seed further bubbles as they rise. Crushed Mentos that fell more slowly created puny fountains that only travelled about 30 centimetres.

“Middle-school teachers are getting their students out onto the baseball field next to their school and doing this reaction, and their students love it,” says Coffey. “It’s a great way to get students excited about science and learn something new.”

Journal reference : American Journal of Physics , DOI: 10.1119/1.2888546

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Mentos® Explosion

How does a soda geyser work?

Are you ready for a blast?

What is the secret behind the reaction between carbonated cola and little mint candies that makes such an explosion? Try it!

Watch the video on YouTube: https://youtu.be/Ot7rZQrEZ4A

You Will Need

At least one 2 liter of soda (we recommend diet cola)

At least 1 roll of mint Mentos® candy (original flavor, not fruity)

Geyser tube (You can purchase one online or make one yourself )

Large area outside that can get messy

Materials & Directions PDF

• Ask student to create a testable question (a hypothesis). Example: Will different numbers of Mentos® change the reaction?
• Place a 2-liter upright, with plenty of space around.
• Remove the Mentos® from the wrappings. You will use one whole pack for each 2-liter bottle, and will need to drop each pack into the bottle all at once. You can use a rolled paper tube or other funnel device to help do this quickly! Ours were commercially available “Geyser Tubes” purchased online.

• Working as fast as possible, open your soda bottle, and drop the whole pack of Mentos® into it.
• Step back and observe the explosion!
• For added scientific fun, experiment and investigate changing different variables. (Examples include but are not limited to: modifying the number of Mentos® dropped, changing the soda flavor, brand, or temperature)

Discovery Questions

Beginning the experiment, during the experiment, after the experiment, how it works.

A carbonated beverage, like soda, is packed with carbon dioxide gas that is dissolved into the soda solution and bonds with water. While the soda is in the bottle, the gas is kept in solution by the pressurized conditions inside the bottle. To create bubbles, the carbon dioxide needs to interact with itself, which means that its bonds with the water in the soda must be broken. A Mentos® candy can help with this.

Each Mentos® candy has thousands of small pores on its surface which disrupt the polar attractions between water molecules, creating thousands of ideal nucleation sites for the gas molecules to congregate. This means that each tiny pore acts like a place where the physical reaction can get a kick start; this is where a bubble of carbon dioxide gas can form and escape!

As the Mentos® candy sinks in the bottle of soda, the candy causes the production of more and more carbon dioxide bubbles. The buoyancy of the bubbles and their growth will eventually cause the bubbles to leave the nucleation site and rise to the surface of the soda to escape.

Bubbles will continue to form on the porous surface and the process will repeat, creating an enormous foamy geyser!

The science behind the Mentos and Coke geyser

Creating a Mentos and Coke geyser is practically a right-of-passage for most kids. It’s explosive, messy, and great fun! But what is really going on when Mentos and Coke collide? Does this time-honoured backyard science experiment work with other sweets and/or soft drinks or is it dependent on some secret ingredients that only these big brands contain? Read on to find out!

A soft drink by any other name

One soft drink is very much like another, right? Yes—to some extent. This means you’d expect similar results whether you complete this experiment with Coca Cola, Fanta, soda water, or any other fizzy drink. 

Thanks to the work of citizen scientists around the globe—accessible via the Internet—we now know that diet Coca Cola is the most effective soft drink when it comes to getting a good surge of spray.

Mentos is a must

While a wide range of soft drinks can be used for this experiment, using Mentos as your chosen candy is a must. Although other sweets, such as M ‘n Ms or Lifesavers, have a similar texture and appearance, Mentos has something going on at a microscopic level that other candies just don’t have. Each Mentos sweet has microscopic pits in its surface that act as nucleation sites. 

A nucleation site is where carbon dioxide molecules that are dissolved in the soft drink come out of the solution and move to their gaseous state. This causes the rush of bubbly gas that escapes out the bottle. Because each Mentos has millions of pits, millions of carbon dioxide bubbles are formed in a very short space of time, resulting in the whooshing soft drink geyser. 

Another factor that is at play is the weight of the Mentos. These candies are heavy enough to sink right down to the bottom of the soft drink bottle. Once the Mentos have settled down there, they wreak havoc, generating huge amounts of carbon dioxide and pushing all the liquid on top of them out through the bottleneck. 

How many Mentos and how much soft drink?

Citizen scientists have set out to find the combination of soft drink and Mentos that would satisfy Goldilocks by being “just right”, and have found that seven Mentos is about the right number for a satisfactory geyser. However, whether you’re using one, seven, or 17 Mentos, they must be dropped into the soft drink at the same time to produce the maximum geyser height. The easiest way to do this is to roll a piece of paper into a tube and place the Mentos inside, then release them in one fell swoop.   

As for the amount of soft drink required, standard 1.5 or 2L bottles available in supermarkets are firm favourites. 

There is no conclusive information on the Internet about the best conditions for this experiment, which opens an avenue for further experimentation. 

Just for fun, why not try some experiments in your own backyard? 

Give it a go! Simply set up a bottle/Mentos combination to use as a control then proceed with subsequent experiments, changing only one variable at a time for each experiment. Variables you could change include: the type of soft drink, the amount of soft drink, the temperature of soft drink, the type of candy, or the number of Mentos or other candies. Rank each experiment according to the size of the geyser it produces.

Here are some tips to ensure your soft drink will give you the ultimate fizz

• Let your soft drink come to room temperature. Like most chemical reactions, the process will occur more quickly if the temperature is warmer. 
• Don’t open the soft drink bottle until you’re ready to start the experiment, otherwise all the fizz will dissipate before the Mentos gets the chance to work its magic. 

Chemwatch is here to help

Let us bring the whizz factor to your chemicals management! We have a range of experts that have many years of experience in labelling, Heat Mapping, Risk Assessments, SDS analysis and more! Contact us on (03) 9573 3100 or at sa***@ch*******.net for more information, or if you have any questions. 

• https://www.stevespanglerscience.com/lab/experiments/original-mentos-diet-coke-geyser/
• https://www.youtube.com/watch?v=LjbJELjLgZg
• https://www.thoughtco.com/does-mentos-trick-work-with-regular-coke-604155

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The Infamous Coke and Mentos Experiment

September 11, 2014 By Emma Vanstone 1 Comment

The science experiments my children talk about for months afterwards are generally the messy ones, like our splatter patterns , glow in the dark oobleck ,  baking soda experiments and the well known coke and mento experiment .

If you try this classic chemis t ry experiment definitely do it outside as it’s VERY messy and sticky. Sometimes you’ll see it called a coke and mento geyse r, as the eruption looks like a geyser!

Coke and Mentos Experiment

You’ll need:.

Coke or other fizzy soda

Instructions

We dropped two Mentos into a bottle of normal Cola and Diet Cola. I used the cheapest brands available in our local supermarket.

Once you drop the Mentos into the coke, stand back as it’s VERY explosive. The trick is to drop the mento in as fast as you can. If too much of the fizz escapes before you add the mento the reaction won’t be as good.

What happens when Coke and Mentos mix?

There are several theories, but it’s thought that the many small pores on the surface of the mento speed up the release of carbon dioxide (CO 2 ) gas from the soda as they give a larger surface area for the reaction to occur over, causing foam to erupt at a super fast rate.

Which soda works best with Mentos?

Any fizzy drink will produce a similar effect, but diet drinks seem to work best, as we found in our investigation. This is most likely due to the particular chemicals in diet drinks.

The reaction isn’t a chemical reaction but a physical reaction! The molecules haven’t been chemically changed, just re-arranged!

See Steve Spangler for a much more thorough explanation of this very cool experiment .

Does the number of mentos affect the height?

More Mentos candies should mean a better explosion, but there is a limit to how many will actually make a difference. We found 7 to be the maximum number we could drop in at once.

More Coke and Mentos Eruption Ideas

Investigate to find out if the type of fizzy drink matters. Does diet soda make a taller geyser?

Try lots of different sodas and diet sodas.

Test fruit-flavoured Mentos instead of mint flavoured.

Find out if the number of mentos affects the height of the geyser.

Investigate to discover what would happen if you left the top off the Cola for a few minutes before adding the Mento.

Use the reaction to power something? Maybe a LEGO car?

Design a device to drop several mentos into the bottle at the same time. Can you find out what the optimum number of mentos for a 2-litre bottle of soda is?

Last Updated on April 9, 2024 by Emma Vanstone

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Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

Reader Interactions

December 17, 2019 at 7:20 pm

It will also work better the warmer the soda is

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Diet Cola and Mentos

Sir Broderick George Richter

 Archduke Dylan Christopher Moore

Bradley James Barrow

The Reverend Kevin Patrick Connelly

Dr. Brady “Tex” Brajavich

IB Physics II

Chris Murray

Janurary 25, 2012

Table of Contents

Introduction

Related Websites Works Cited

            Before we developed our hypothesis and method, we each brought a large amount of background information to the experiment. We had all seen many YouTube videos featuring the famous Diet Coke and Mentos experiment and knew its basic parameters. Further research yielded the following background information.

            First, we learned that the massive buildup of pressure occurs when carbonation causes bubbles to accumulate on the surface of the Mentos. These bubbles rapidly expand and are forced out of the small opening of the bottle, creating a geyser. Second, we learned that the aspartame in diet cola lowers the surface tension of the liquid, making it specifically more conducive to creating a large plume. Based on this information, we began to wonder how different amounts of cola would react to the same number of Mentos and if the velocity of the plume had any relation to the height.

            Our independent variable was the amount of soda in the bottle. Our dependent variables were height and velocity of plume. Our constants were the type of soda used (Big K Diet Cola) and number of Mentos used (10). We used the equation V=D/T to find the average velocity of the plume, in which D is the height of the plume and T is the amount of time it took to reach its maximum height.

Hypothesis: If the amount of soda in the bottle decreases, then the height of the plume and velocity of the liquid will also decrease because there will less liquid with which the Mentos can react.

To Table of Contents

We conducted our experiment at the Byrom basketball courts, an open area with a wall in the background for scaling and measurement purposes. We set each bottle of soda a foot from the wall to prevent it from interfering with the plume. We set up the camera at the edge of a marked wall-ball court where it stayed for the duration of the experiment. For each trial, we placed 10 Mentos into a length of PVC piping and held a plastic card to the end to keep them in.  after counting down, we then unscrewed the cap of each bottle as quickly as possible. We would then cover the opening with the PVC piping and slide out the plastic card, causing the Mentos to fall into the bottle. The Mentos and cola then reacted, which was captured on camera. At one point during the experiment, the sun set and we had to use car headlights to illuminate the court. We took the footage we acquired from the trials and put them into Logger Pro, using the height of the court as a reference. We measured the height of the plume from the top of the bottle as well as the average velocity on its’ way up. We ran 3 trials at 6 different volumes for a total of 18 videos. We then charted and graphed the heights and velocities from each of these into three separate graphs.

Materials List:

20 Diet Cola bottles

14 Mentos rolls

Video Camera

Volume measurement device

  Meter stick

  To Table of Contents

This graph shows all trials of heights, so you can see the outliers:

Data file: text .:. excel, calculation of velocity: velocity = distance/time.

            As the data table and graphs show, the average peak height of plume was not when the bottle was full as we had predicted, but at 1725mL.

            Uncertainties were found as follows: For volume, we used a measuring device that had intervals of 50mL, giving us an uncertainty of +/- 25mL. For height, our uncertainty was human error in Logger Pro, so it was not exact. We estimated +/- 3cm. For time, our video in Logger Pro had a time of 0.2 seconds between each slide, making our uncertainty +/- 0.1.

            We have concluded that there is an optimal amount of soda to maximize the height of the foam explosion. It peaked at the second highest amount of soda, and we were surprised with the outcome. Our hypothesis was not supported, because there is an amount of soda between full and empty that creates a bigger plume. When we discovered the full soda did not achieve the same height as the trials with slightly less we were shocked. We had assumed that the more liquid there was the more aspartame and carbonation there would be to react. We could not explain this phenomenon but we theorize that the extra space in the bottle allowed more bubbles to form prior to the explosion, therefore providing a higher plume because the bubbles are more easily propelled than the liquid. However, there are many sources of error that could have altered our data. When the sodas were opened some of the reacting gases may have left the bottle at varying speeds, and there were inconsistencies in pouring out the soda as we attempted to do it quickly. Also, the mechanism we used to drop the Mentos was not perfectly efficient, resulting in Mentos that were not all dropped at the same time or speed. And finally some human errors such as shaky video and not exact measurements in Logger Pro. We could have improved the experiment by performing more trials for each amount of soda and by being more careful when following the steps of the method.

Related Websites

Works Cited

http://www.eepybird.com/featured-video/the-extreme-diet-coke-mentos-experiments/

http://www.newscientist.com/article/dn14114-science-of-mentosdiet-coke-explosions-explained.html

http://www.youtube.com/watch?v=9vk4_2xboOE

http://dsc.discovery.com/videos/mythbusters-diet-coke-and-mentos.html

http://thetartan.org/2007/2/19/scitech/how

Fizzing Chemistry Experiment: Coke and Mentos Experiment

Categories Science Experiments

The Diet Coke and Mentos experiment is exciting to do for kids of all ages. We created this Coke and Mentos experiment lesson plan as part of our chemistry experiments for kids because it’s literally exploding with fizzing soda reactions and chemical changes!

But how exactly does the diet coke and mentos experiment work?

It all starts with two seemingly ordinary items—a bottle of Diet Coke and a roll of Mentos candies. When combined in a specific way, the coke and Mentos create a dramatic fizzing chemistry experiment that sends soda shooting into the air like a geyser.

Imagine witnessing a miniature volcanic eruption right in your own backyard!

The carbon dioxide in the Diet Coke and the bumpy surface of the Mentos candy are the key ingredients for this visually stunning display during the coke and mentos experiment lesson plan.

Table of Contents

Diet coke and mentos experiment lesson plan: the magic of the diet coke and mentos geyser.

The diet coke and mentos experiment lesson plan is a simple yet astonishing experiment that demonstrates the power of a chemical reaction in action.

With just a bottle of Diet Coke and a roll of Mentos candies, you can create a captivating eruption that surpasses expectations.

When the Mentos come into contact with the soda, a rapid release of carbon dioxide gas occurs, resulting in an explosive fizz.

The pressure builds up so quickly that the liquid is forcefully expelled in a powerful stream, creating the geyser-like effect.

How Does the Diet Coke and Mentos Experiment work?

The coke and mentos experiment lesson plan is a fascinating display of a chemical reaction in action and also that of a physical change causing a reaction between two ingredients.

When Mentos candies are dropped into a bottle of Diet Coke, it causes a rapid release of carbon dioxide gas, resulting in a dramatic eruption. But how does this reaction occur?

The reaction is primarily caused by two factors: the rough surface of the Mentos candy and the carbon dioxide gas dissolved in the Diet Coke.

The surface of the Mentos candy contains tiny pits and crevices, which provide numerous nucleation sites for gas bubbles to form.

When the candies are dropped into the soda, these nucleation sites allow the carbon dioxide gas to rapidly escape from the liquid.

The carbon dioxide gas in the Diet Coke is dissolved under pressure. When the bottle is opened or the candies are added, the pressure inside the bottle decreases.

This change in pressure triggers the gas bubbles to form on the rough surface of the Mentos. The gas bubbles rapidly expand, creating a fizzing effect.

As more and more gas bubbles are produced, the pressure builds up inside the bottle, eventually leading to an explosive release of the gas.

The liquid is forced out of the bottle in a powerful stream, creating the geyser-like eruption.

Is Fizzing a Chemical Change?

In fact, the reaction between the Mentos and Diet Coke is primarily a physical reaction rather than a chemical one.

The candy’s rough surface provides the necessary conditions for the gas bubbles to form quickly.

The process happens so rapidly that it creates a visually captivating and exciting reaction.

Supplies for a Diet Coke and Mentos Geyser

Here is what you’ll need to create this fizzing chemical reaction and complete your coke and mentos experiment lesson plan. These links are to Amazon or other affiliates of STEAMsational.

• STEM worksheet (click the image below to download)

Coke and Mentos Experiment Kits

Here are some alternative options for doing this fizzing chemical experiment and coke and mentos experiment lesson plan with a group of students.

• Classroom Geyser Pack (for 10 students)
• Steve Spangler’s Extreme Geyser Tube
• Observable Forces Classroom Bundle

If you love science and STEM but don’t like hunting for supplies, we love the Mel Science kits. They have options for elementary and middle school, and each kit comes with all the supplies needed for each experiment!

Diet Coke and Mentos Experiment STEM Extensions

Here are some STEM extensions you can add on to your coke and mentos experiment lesson plan.

Fizzing chemistry experiment variable exploration

Encourage students to experiment with different factors and observe their effects on the geyser. They can investigate elements such as the brand of soda, the size or shape of the candies, the temperature of the candies, or their surface roughness.

By systematically testing these variables, students can collect data and analyze how they impact the reaction. This exploration promotes critical thinking, hypothesis development, and data analysis skills.

Coke and mentos experiment lesson plan data analysis

Extend the experiment by incorporating data analysis and charting. Students can measure and record information from multiple trials, such as the height or duration of the geyser.

By organizing and graphing the data, students can visually explore the relationships between different variables, enhancing their mathematical skills and solidifying their understanding of scientific principles.

Geyser design engineering challenges

Introduce design engineering challenges related to the Mentos and Diet Coke Geyser.

Assign students the task of designing and building a device to control the force or direction of the geyser or develop a mechanism to initiate or stop the reaction.

This extension allows students to apply their knowledge of engineering, physics, and problem-solving to create innovative solutions.

Coke and mentos experiment science fair project

Encourage students to develop a science fair project based on the coke and mentos experiment lesson plan. They can formulate their own research question, design experiments to test their hypotheses, collect data, and present their findings.

Soda and mentos science project hypothesis: When Mentos candies are added to different brands of soda, the brand with the highest carbonation levels will result in the most significant eruption.

Based on prior knowledge and observations, the hypothesis predicts that the level of carbonation in soda will affect the intensity of the reaction when combined with Mentos candies.

Soda with higher levels of carbon dioxide gas dissolved in it will have a greater potential for gas release when the nucleation sites on the Mentos’ rough surface trigger bubble formation.

The with the highest carbonation levels is expected to produce the most substantial eruption when combined with Mentos.

More Chemistry Experiments to Try

Here are some other fun chemistry experiments that kids will love after you complete your coke and mentos experiment lesson plan.

• 15 Explosive and Awesome Chemistry Sets For Kids
• What is a Chemical Reaction for Kids?
• Chemical Reactions! How to Turn a Penny Green Experiment
• The Effect of Temperature on Reaction Time

How to Do the Mentos and Diet Coke Experiment Step by Step

The coke and mentos experiment lesson plan offers a tangible way for students to explore chemical reactions. Through firsthand observations, students can understand concepts such as nucleation sites, gas solubility, and the relationship between surface area and reaction rate.

This experiment also fosters critical thinking, logical reasoning, and problem-solving skills. Get the complete coke and mentos experiment lesson plan below!

Get the printable step-by-step directions for the coke and mentos experiment lesson plan below!

And don’t forget to use our free mentos and coke experiment worksheet that you can download by clicking the image below to complete your fizzing chemistry experiment!

Print a lot of papers? Get $10 your HP Instant Ink order when you use this link.

Diet Coke and Mentos Geiser

Looking for a simple and exciting science experiment? Look no further than the Diet Coke and Mentos experiment lesson plan! With just two ingredients and one worksheet, all you have left to do is teach the lesson!

• Paper towels
• Measuring tape
• Science notebook

Instructions

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Diet Coke and Mentos Eruption

Love fizzing and exploding science experiments ? YES!! Well, here’s another one the kids are sure to love! All you need is a pack of Mentos candy and Diet Coke. You might think there’s a chemical reaction happening, but this Mentos and soda experiment is a great example of a physical reaction.

Mentos and Diet Coke Eruption

Is the reaction between Coke and Mentos a chemical reaction? With all the fizzing and foaming, it looks like there must be a chemical reaction between the Mentos and diet Coke, like our elephant toothpaste or baking soda and vinegar volcano .

However, you might be surprised that this experiment is an example of a physical change . Read on to find out why Mentos makes Coke explode if there is no Mentos and Coke chemical reaction.

• 2 liter Diet Coke
• Mentos candy
• Index cards

Diet Coke and Mentos Experiment Instructions

STEP 1: Roll up an index card into a tube and tape it together. The tube needs to be large enough to hold the Mentos and still allow them to fall out easily.

STEP 2: Tape the tube to the top of your bottle, but only tape on one side. An index card needs to be able to fit underneath the tube from one side.

STEP 3: Place the other index card under your tube and attach your string to it with tape.

STEP 4: Drop the Mentos into the tube.

STEP 5: Now back away with the string in hand. Pull the string, which will also pull out the index card, allowing the candy to fall in.

💡 NOTE: If you can, set up a measuring tape in the background to help record the height of the eruption. Or place a piece of tape at a certain height on a wall or garage door to get an approximate idea of the height of your eruptions!

If you’re recording the eruption, use the slow mode function to capture the peak height more easily. You’ll be able to pause and check out the fountain height.

Watch the excitement from a safe, and clean distance!

Coke and Mentos Science

Inside the Coke or soda is dissolved carbon dioxide gas, which forms a bond with the water, making the soda taste fizzy when you drink it. This is called a carbonated beverage. Usually, you can find these gas bubbles coming from the soda, creating a bit of foam in a glass.

However, much of the gas is trapped on the surface of the soda, waiting to get out! It is held there by a scientific concept called surface tension . Once the mentos are added, the gas bonds break down more quickly due to the candy’s rough surface.

Adding Mentos speeds up this process because more bubbles form on the Mentos’s surface than on the bottle’s side, pushing the liquid up. This is an example of a change in the state of matter ; the carbon dioxide dissolved in Diet Coke moves to a gaseous state.

💡Did you know you can try this experiment with other candies and even pennies? That’s because it’s a physical change instead of a chemical one! Go ahead and experiment!

How to Apply the Scientific Method

Mentos candy are relatively dense and sink quickly, causing a powerful, fast eruption; EYE PROTECTION is recommended if you are standing close!

You can extend this Mentos and coke experiment below with additional suggestions. Older kiddos will benefit from learning about and incorporating the scientific method !

If you want to set up an experiment with several trials, pick one thing to change, such as the type of soda! Don’t change everything! You need to change the independent variable and measure the dependent variable .

You can also get kids started by writing down their hypotheses before diving into the experiment. What do they think will happen when the Mentos is added?

After performing the experiment, kids can conclude what happened and how it matched their initial hypotheses. You can always change a hypothesis upon testing your theory!

Expand the Experiment

What about crushed Mentos? Change the size of the Mentos by breaking them into small pieces to test whether that changes the amount of foam produced.

What about soda flavors? Compare different types of soda while adding the same amount of Mentos to each. Which produces the most foam, diet coke or original coke? How about Orange, Root Beer, or Sprite? Does club soda or seltzer erupt?

What about temperature? Does ice-cold Diet Coke work better than room-temperature Diet Coke?

What about mint flavors? Do Mentos mints or Fruit Mentos work better?

What about alternative items? What can you try instead of Mentos candy? Will it produce the same results or a similar height of eruptions? Other options could include pennies, rock salt, or different size candy!

Mentos and Coke Science Fair Experiment

Science projects are an excellent tool for older kids to show what they know about science. They can also be used in various environments, including classrooms, homeschools, and groups.

Kids can take everything they have learned about using the scientific method , stating a hypothesis, creating variables , and analyzing and presenting data.

Want to turn this Diet Coke and Mentos rocket into a cool science project? Check out these helpful resources below.

• Easy Science Fair Projects
• Science Project Tips From A Teacher
• Science Fair Board Ideas
• Scientific Method Explained

More Fun Science Projects to Try

• Skittles Experiment
• Baking Soda and Vinegar Volcano
• Lava Lamp Experiment
• Growing Borax Crystals
• Pop Rocks and Soda
• Magic Milk Experiment
• Egg In Vinegar Experiment
• science experiments for kids

Printable Science Projects For Kids

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• Know the Words Science vocabulary pack  includes flashcards, crosswords, and word searches that illuminate keywords in the experiments!
• My science journal writing prompts  explore what it means to be a scientist!!
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