A Diet Coke and Mentos Eruption
Grade Level: Grade 5
Strand: Understanding Matter and Energy
Topic: Properties of and Changes in Matter
Specific Expectations:
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Identify indicators of a chemical change
Distinguish between a physical change and a chemical change
Materials Required:
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4/5 mentos
One 2L bottle of diet coke
Safety glasses
Procedure: (include illustrations)
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Go outside and discuss with the students the different possible outcomes of
putting a penny, piece of chewed and un-chewed gum, etc. into the diet coke
While outside show the students what happens when you place 4/5 mentos in a
bottle of diet coke
Come back into the class and brainstorm things that could change the results of
the fountain. (eg. Type of candy, amount of mints, type of soda, etc.)
Discuss whether the chemical reaction was a physical change or a chemical
change
Scientific Explanation: (in detail)
Scientists believed that the gum arabic found within the mentos is the reason for
the reaction to occur with the diet coke. However, chemists have discovered that
materials that do not contain gum arabic also cause the reaction with soda. Mint
flavoured mentos are used because the fruit-flavoured mentos have a smooth coating
which slows the reaction to occur with the soda. The chemists have agreed that the
primary cause of the reaction is a physical change, not a chemical change. Chemists
believe that a nucleation site, a liquid that is supersaturated with gas, is an area where the
gas is able to form bubbles. Mentos have been found to contain many nucleation sites that
cause an incredible number of bubbles to form when it is dropped in a bottle of soda. The
weight of the mentos, considering they are heavy enough to sink to the bottom of the
soda, causes the mentos to react with the soda all the way to the bottom. The escaping
bubbles quickly turn into raging foam, and the pressure of the foam to build, which cause
a major geyser to result.
References:
EeepyBird.com. Entertainment for the Curious Mind. “Science.” (2005-2009).
http://www.eepybird.com/science.html
Ministry of Education. (2007). The Ontario Curriculum: Science and Technology 1-8.
Ontario : Queen’s Printer for Ontario.
Wikepedia. Diet Coke and Mentos Eruption. (2010).
http://en.wikipedia.org/wiki/Diet_Coke_and_Mentos_eruption
Opportunities and other considerations:
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Gives students a visual of the scientific experiment (show a youtube video)
Hook into understanding the difference between physical and chemical change
For safety and clean up issues, it is best to conduct this experiment outside
because the geyser of soda will erupt to great heights and in turn create a mess of
soda around the bottle
Students should also be given safety glasses for safety issues of flying soda
getting into their eyes
A variation to the experiment consists of making the bottle rocket up by closing
the cap shortly after the mentos are inserted and then slamming the bottle into the
ground cap first. The explosion will create a reaction like a rocket.
To demonstrate the various nucleation sites available around the house. First, coat
the inside of a small class with vegetable oil. Move the glass around to get a nice
smooth coating of oil and then pour in some soda. No fizz will result because
there are no nucleation sites. Now sprinkle in some granulated sugar. Lots of fizz
results because of there being lots of nucleation sites within the sugar.
Glossary:
Physical change: A change in the shape, appearance, or state of material so that it can
still be recovered as the original material. Physical changes are reversible. (eg. Ice to
water to ice)
Chemical change: A change in matter that implies the formation of a new substance. The
changes are irreversible. (eg. Wood to smoke to ash)
Nucleation Sites: A place where the gas from the liquid (soda) is able to form bubbles.
Nucleation sites can be scratches on a surface or specks of dust—anywhere that you have
a high surface area in a very small volume.
Names of Presenters: Heather Preikschas and Bruce Monkman