Soda Fountain

What you’ll need:

  • Mentos mints
  • 2-liter of diet cola at room temperature
  • Sheet of paper


  1. Place the bottle of soda on a flat surface, outside, clear of anything in the area that could be hit by the soda eruption.
  2. Roll up your sheet of paper and insert the top into your soda bottle, without allowing it to dip into the soda.
  3. An adult can gently drop 3-4 mints into the tube in the soda bottle and quickly move away from the bottle.  The key is for all the mints to drop into the soda at once (vs. one at a time).  One way to do this is to roll up the paper tube, put your finger at the bottom, then add the mints so that your finger is all that’s holding the mints in the tube.  Then, place the tube right over the opening of the bottle and remove your finger so all the mints drop in at once.  Then, run so you won’t get sprayed and can see the geyser!

What causes the soda to spray out of the bottle?  Soda has carbon dioxide in it.  That’s why, if you shake a soda, then open it, it sprays out at you.  It’s also what makes the little foam you see when you first pour soda into a glass.  When the mints drop into the soda, a gas is released quickly in the form of an eruption that pushes the soda out as spray from the bottle.

You can perform the geyser experiment multiple times with different brands of diet cola, diet cola that has been stored at different temperatures, or using different numbers of mints, to see what will result in the best geyser!

Check out other science and math activities from Camp Little Victors: