This favorite experiment needs space, Mentos and plenty of soft drink. The Steve Spangler Geyser Tube makes it VERY easy to drop multiple Mentos tablets into the soft drink to create a magnificent geyser and also learn LOTS of science!

Materials List

2 L Diet Cokementos geyser materials

Mentos Geyser Tube (available from us with Mentos)

Mentos packet



1. The geyser does go high into the air and therefore should be conducted OUTSIDE.


Undo the lid from the Coke bottle and attach the Mentos Geyser tube.

mentos geyser step 1mentos geyser step 3

Insert the plastic release into the holes at the base of the tube. Thn start to place the Mentos lollies into the tube.

IMPORTANT: hold the release rod in place to prevent the rod from coming out of the hole, the lollies falling into the Coke. This may happen and cause the release of Coke while you are holding it (Coke Shower!)

mentos geyser step 4mentos geyser step 5

Once the lollies have been added, attach the lid and get ready to release (outside) for a mangnificent way to explore physical changes!

mentos geyser step 6c

Check out the ‘Wacky Science’ video of this experiment and ‘What’s Going On’ series link. They are currently ‘In Production’, so check back soon…..



This is a very FUN way to explore the chemistry of dissolved gases, specifically how physical changes occur.

Normally, most of the Carbon dioxide gas is in a dissolved formed called aqueous (aq) due to the high pressure inside the bottle. When you open the bottle, the pressure is released and the dissolved gas changes to a gaseous form (g).


CO2 (aq)  ——->  CO2 (g)                   moves to the right when pressure is decreased


This process of changing the dissolved gas into a gas form occurs faster when the dissolved gas has a site for this change to occur. These sites called nucleation sites are on the sides of the bottle or glass (thats why you see bubbles form on the sidesglasses).

When you drop the lolly in, the current research indicates that the small divots in the surface of the tablet provides nucleation sites for gas bubbles to form. As there are so mant sites for bubbles to form, they form VERY quickly.

Mentos tablet explanation2


The sudden increase the large gas bubbles inside the bottle causes the pressure to increase inside the bottle and pushes the liquid out of the top of the tube to create the famous ‘Geyser’ effect.

If you want more detailed explanations of the science terms, ideas to make this an experiment by changing variables etc to see how temperature, surface area can affect gas solubility then check out the following below:



If you would like

– more details,

– pictures of the second half of the experiment

– information on how to investigate this further

– links to everyday examples

– management hints & teaching pointers (5P Teacher develpoment program)

 ….. then why not subscribe to one of the following


(1) Crazy science Club

Crazy Science Club slider5

(2) 5P Teacher Training course called ‘Looney Lab  Classroom Creations

Looney Lab Classroom Creations2


Or you can purchase the ‘Bright Sparkes Guide’ of this demonstration only ($2.50) which has:

  • HD pictures of experiment steps
  • Detailed explanation of science
  • Mini-challenge section (another experiment)
  • Making it a ‘Scientific Method’ experience
  • Graphing opportunities
  • REAL links and descriptions to everyday examples of concept.







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