How can you make popcorn kernels
dance?
Explore a chemical reaction that can make popcorn ‘dance’.
Setting: Indoors
Time: < 30 minutes
Concepts: chemical reactions, acids-bases
Skills: predicting, observing
Subject(s):
 Chemistry
Ages:
 12-14
Materials:
• Baking soda (1 tsp)
• Vinegar (¼ cup)
• Water (1 cup)
• Un-popped popcorn kernels
• Measuring cup
• Shallow pan
• Tall glass or jar
• Teaspoon
What to do!
1. Place the glass in the centre of the shallow pan and add several popcorn kernels into the
glass.
2. Predict what will happen when each of the following steps occur:
a) 250 mL (1 cup) of water is poured into the glass.
b) 60 mL (1/4 cup) of vinegar is poured into the glass containing the water.
c) 5 mL (1 tsp) of baking soda is added to the vinegar solution (without stirring).
3. Pour 250 mL (1 cup) of water into the glass and observe what happens.
4. Pour 60 mL (1/4 cup) of vinegar into the water in the glass and observe what happens.
5. Add 5 mL (1 tsp.) of baking soda to the vinegar solution (do not mix!) and observe what
happens. Is this what you expected to happen? Why or why not?
What’s happening?
When the vinegar and baking soda are combined, a chemical reaction occurs between the
acetic acid in vinegar and the sodium bicarbonate in baking soda. This causes a release of
chemical energy and the formation of a gas (carbon dioxide).
Some gas bubbles that form will adhere (stick) to the outside of the popcorn kernels and raise
them to the surface of the liquid. This is because the kernels and bubbles together have a lower
density than water and thus rise to the surface of the liquid. At the surface, the gas bubbles
burst, releasing the carbon dioxide into the air. Once the bubbles have burst, the density of the
kernel is once again greater than that of water and the kernel sinks to the bottom of the glass.
Why does it matter?
Acid-base reactions are often used in baking to make bubbles form in cakes or cookies as they
are baking. This helps make baked goods light and spongy, rather than heavy and dense.
1
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How can you make popcorn kernels
dance?
Investigate further!
•
•
Try this experiment with objects such as rice, dried kidney beans or paper clips instead
of popcorn.
Replace the baking soda with salt or sugar and see if you get the same effect.
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