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From the Lab Bench: Mentos Fountain
««« By Milan Sanader
Milan Sanader is a science teacher at Holy Name of Mary Secondary School
(Dufferin-Peel Board of Education in Mississauga), and Chair of the STAO Secondary
Curriculum Connection: Grades 8 and 9, Physical bottle are perfectly aligned. Hold the test tube secure-
Changes; Grade 11U Chemistry and Grade 12C ly in one hand.
Chemistry, Solubility or Surface Tension. 7. With your other hand, quickly remove the card and get
out of the way as the Mentos fall into the bottle. Don’t
In this teacher demo, Mentos mints are used to unleash drop the test tube!
the dissolved carbon dioxide in a 2 L bottle of carbonated
pop, producing a 2-3 m fountain. What happens?
A 2-3 m fountain of pop is observed. Only about 10-20 % of
Materials the original volume of pop remains in the bottle at the end
• Plastic Apron of the demonstration.
• Eye protection
• Package of Mentos mints How does it work?
• 2 L bottle of diet carbonated pop The gelatine and guar gum released as Mentos dissolve
• Large test tube (the same diameter as the pop bottle) disrupt the surface tension of the water within the pop
• Business card bottle. Further, the surface of each Mentos is covered with
tiny pits. Each pit becomes a nucleation site for bubbles of
Procedure carbon dioxide to form. A similar effect is sometimes
Note: Do this activity outside on the lawn to avoid having to observed when pasta is added to boiling water.
clean up the mess. Presumably, materials released from the pasta disrupt the
1. Put on eye protection and a plastic apron. surface tension of the water enough to cause a rapid
2. Place the pop bottle on a flat stable surface like a pic- expulsion of dissolved gases, causing the pot to boil over.
3. Add the Mentos to the test tube so that the mints are Teaching Suggestions
stacked one on top of the other. This activity is useful when discussing surface tension or
4. Cover the test tube with card. gas solubility in SCH3U or SCH4C. It could also be used as
5. Open the bottle. an example of a physical change in grades 8 and 9.
6. Invert the test tube and card and place it on the mouth Diet pop is recommended because pop with sugar leaves a
of the bottle so that the test tube and the mouth of the sticky residue which can be difficult to clean up.
From the Lab Bench Volume 38 • 1 September 2006
CRUCIBLE online stao.org
An example of a Mentos
fountain – a demonstration
you can do with your class.
Photo courtesy of Milan
Used with permission.
“From the Lab Bench” is a new regular feature submitted
by the STAO Secondary Curriculum Committee. “From the A mentos fountain at night!
Lab Bench” will feature simple yet effective demonstra- Photo courtesy of Ian DeBarry.
Image found at Flickr:. Used
tions/lab ideas that teachers may photocopy and use in
with permission of owner.
their classrooms. The procedures involved are simple and Visit Mr. DeBArry’s Flickr site at:
use readily available materials. Crucible welcomes all http://www.flickr.com/
submissions for “From the Lab Bench.” Please submit photos/outstandingstandin/
your favourite lab or demonstration ideas to “From the
Lab Bench.” All submissions used in the Crucible are
eligible for STAO bucks. Please see page 6 for details on
how to make a submission to Crucible. Include your name,
school name, contact information and the curriculum
connection for the activity.
From the Lab Bench – Page 2 Volume 38 • 1 September 2006