Extreme Drawing

Mentos and coke experiment: why the cola shoots up

Kitchen science experiment

Drop the mints and run

Cola is full of dissolved carbon dioxide gas. Mint sweets are covered in tiny pits where bubbles can form, so when the mints drop in, all that gas turns into bubbles at once and pushes the cola out in a fountain. Nothing new is made: it's a physical change.

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  • Ages 5+
  • 10 minutes
  • Outdoors only
Painted illustration of a cola bottle on the grass shooting up a tall fountain of foam as mints drop in, the painter in goggles laughing beside it.

Quick facts

Age
5 to 10
Time
10 minutes, plus a hose-down
Mess
High and sticky: outdoors only
Adult needed
Yes, to drop the mints and keep everyone back
You need
A 2-litre bottle of diet cola and a roll of Mentos-style mints (a few euros or dollars)
On screen / for real
Both

Cola and mints in Extreme Drawing

In the free Science tab, tap Eruptions and choose Cola and mints, then tap the paper where the bottle should stand.

After a short moment a fountain of cola shoots up for about three seconds, getting weaker as the gas runs out, with a rushing hiss. It rains back down in a wide ring of sticky brown drops that soak in and stain the paper.

Then the fun starts, because the cola stays sugary: ants come for it and fruit flies find it. Put the page in the oven and the cola cooks down to caramel. It's everything you'd rather not have on your kitchen floor.

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Painted illustration of the painter, goggles on his beret, studying a bottle foaming over in stripes, with red cabbage juice in pink and green glasses and fizzing baking soda.

Do it for real

The cola geyser, outside

You need

  • A 2-litre bottle of diet cola at room temperature (much less sticky than regular cola)

  • A roll of chalky mint sweets: Mentos are the classic, about 5 to 7 of them

  • A sheet of paper rolled into a tube just wider than the mints, and a piece of card

  • Safety goggles

  • An open space outdoors: grass or a path, away from cars, windows and walls

  • A watering can or hose for afterwards

  1. Find a good spot

    Stand the bottle upright on flat ground outside. Goggles on for everyone.

  2. Open the bottle gently

    Twist the cap off slowly so it doesn't fizz over, and put the cap away.

  3. Load the tube

    Hold the card under the paper tube like a trapdoor and stack the mints inside.

  4. Predict

    How high will it go? Higher than you? Higher than a door? Mark your guess on a fence or wall.

  5. Drop and step back

    The adult holds the tube over the bottle neck, slides the card away so all the mints drop at once, and everyone takes three big steps back.

  6. Measure and clean up

    Compare the height with your guess. Then wash the sticky patch away with water and recycle the bottle.

Myth check

Will your stomach burst if you eat Mentos and drink coke?

No. That's a playground myth. You swallow far less at once than a whole bottle, the gas has room to escape, and it comes back up as burps. It doesn't feel nice, though, and gulping fizzy drinks fast can make your tummy ache, so it's not a good dare. Do your geyser outside, in a bottle.

For kids

Cola is full of hidden gas waiting to make bubbles. The bumpy mints give the bubbles millions of places to start, all at the same time, so the gas shoots out and takes the cola with it.

Why the cola erupts

For grown-ups. Cola is carbonated: carbon dioxide is dissolved in it under pressure, more than can stay dissolved once the bottle is open. To come out, the gas needs places where bubbles can start (nucleation sites). A smooth bottle offers very few, so an open cola goes flat slowly. A mint's surface is covered in microscopic pits, each one a nucleation site, and the mints sink fast, so bubbles start all the way down the bottle at once. The gum arabic in the mints and the sweetener in diet cola also lower the surface tension, which makes bubbles form even more easily. The rush of gas pushes the cola up and out. No new substance is made, so this is a physical change, not a chemical reaction: the carbon dioxide was in the cola all along.

Predict, then try next

Each of these needs another bottle, so pick the one you're most curious about.

Cold cola or warm cola?

Warm liquids hold less gas. Which fountain goes higher?

Diet or regular?

Two bottles side by side. Most people find diet goes higher. Does yours?

One mint or seven?

Does the height keep going up with more mints, or stop at some point?

Something else rough?

Try a teaspoon of salt or sugar. Which works better than the mints, and why might that be?

For teachers

Cola and mints in the classroom

A memorable way into gases and particles: it fits KS2 Year 4 states of matter (gases in a liquid) and NGSS 5-PS1-1 (matter is made of particles too small to be seen). It's also a good contrast with baking soda and vinegar: one makes a new gas, the other lets out gas that was already there. Show the app eruption on the whiteboard, then do one bottle in the playground.

Ideas for teachers

Mentos and coke questions

Why do Mentos make coke erupt?

The mints' rough surface gives the dissolved carbon dioxide in the cola millions of places to form bubbles at once. So much gas comes out so fast that it pushes the cola up and out of the bottle.

Is Mentos and coke a chemical reaction?

No, it's a physical change. The gas was already dissolved in the cola; the mints only let it escape all at once. Nothing new is made.

Does diet coke work better than regular coke?

Usually, yes: diet cola tends to go higher, and it's far less sticky to clean up. Regular cola still erupts.

What happens if you eat Mentos and drink coke?

You'll probably burp a lot, and your tummy may feel uncomfortable, but your stomach won't burst. That's a myth.

How many Mentos should you use?

Five to seven mints in a 2-litre bottle gives a good fountain. Drop them all at once with a paper tube so the gas comes out together.

More to try

Painted illustration of the painter finger-painting a big sheet covered in hand prints, paint splats, a toothpaste squiggle, glitter and a cracked egg.

Messy play

All the splatter and splash on screen, and none of the cleaning up.

Make it rain cola, minus the sticky floor

Science tab, Eruptions, Cola and mints. Then see who turns up for the sugar.

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