Pop Rocks® Expander | Science Experiment

Mixing Pop Rocks and soda let's you discover the secret behind the famous popping candy.

Pop Rocks® Expander: A Pop Rocks Science Experiment
How do Pop Rocks work? With our Pop Rocks experiment, you’ll learn how these popular candies create that amazing signature “popping” sensation in your mouth. When you mix Pop Rocks and soda, you’ll be amazed at the intense experience it creates. With our Pop Rocks Expander science experiment, you’ll discover the secret behind the famous popping candy!

Pop Rocks is one of the greatest candy inventions of all time. When you dump a few of those tiny pebbles onto your tongue, they instantly fizz, pop and snap in your mouth. What’s going on here? How do Pop Rocks work? As scientists, we’ve devised a way to figure out the popping secret behind this famous candy. Get ready to expand your mind — AND a few balloons. This Pop Rocks experiment is a fun combo lesson in several scientific principles, including air, chemistry — as well as food and candy science. Gather up some Pop Rocks and a few other ingredients and get ready to learn about Pop Rocks candy!

Pop Rocks® is a registered trademark of Pop Rocks, Inc.
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Experiment Materials

  • Pop Rocks® (multiple flavors)
  • Balloons
  • Funnel
  • 12-16 oz bottles of soda (a variety)

Experiment Videos



The easiest way to get an entire package of Pop Rocks into a balloon is to use a small kitchen funnel. Place the narrow end of the funnel into the mouth of the balloon.


Empty the Pop Rocks packet into the funnel. Make sure the funnel is empty by giving it a few firm taps. You should be able to see into the balloon.


Place the opening of the balloon over the mouth of a bottle of soda. The balloon should hang down beside the bottle. Stretch the opening of the balloon over the mouth of the bottle but make sure the valuable candy content doesn’t get dumped into the soda. You don’t want to drop the candy before you’re ready.


Grab the balloon at it lowest point, lift it up, and dump the Pop Rocks into the soda. Be sure to observe what’s happening inside the bottle as the liquid reacts to the candies. The balloon will be inflating even if the change is very slight.

How Does It Work

The secret behind that famous Pop Rocks candy “popping” sensation is pressurized carbon dioxide gas (CO2). Each of those tiny little candy pebbles contain a small amount of the gas. When they burst free from their candy shells, these tiny gas bubbles make that irresistible popping sound. Need more proof? Try finding a relatively large bag of Pop Rock candies and use a spoon to crush them against a hard surface. Once you achieve enough pressure, you’re likely to hear a “pop” similar to the sound you hear when you have that Pop Rock candy on your tongue.
What caused the balloon to inflate in this Pop Rocks experiment? Although there is some pressurized carbon dioxide gas suspended within Pop Rocks candy, it isn’t enough to cause even the small amount of inflation you observed. That’s where the CO2 in the soda comes into play. The soda, a carbonated liquid to begin with, contains a lot of pressurized CO2. When the Pop Rocks candies are dropped into the soda, some of the gas inside the soda collects in gazillions of bubbles on the candy’s microscopic surface nucleation sites (imperfections, dents, bumps). Some of the gas escapes from the water and corn syrup that hold it and it moves upward. It fills the space at the top of the bottle and then moves up, up, up — then into the balloon — as the volume of CO2 increases.

Science Fair Connection

This Pop Rocks and soda experiment can be turned into a fantastic and fun science fair project that will wow your family and your friends. Although mixing Pop Rocks and soda is a fun experience by itself, it really isn’t a science project experiment. To use Pop Rocks ingredients to create a super cool science experiment, you’ll need to introduce a variable, or something that changes. There are a number of different variables that you can choose to get that coveted blue ribbon. However, remember that whichever variable you choose, you will need to keep everything else the same.
• Test whether the temperature of the soda makes a difference in the amount of carbon dioxide released.
• Use different types (or brands) of soda to see which one releases the most carbon dioxide gas.
• Test different Pop Rocks flavors to see if the flavorings used ultimately change the amount of carbon dioxide released into the balloon.
Those are just a few of the possible variables you could use. You’re creative, come up with your own!

How are Pop Rocks made?

According to information from the manufacturer, Pop Rocks, Inc., this popular candy starts out just like any other hard candy — by combining sugar, lactose (milk sugar), corn syrup and flavoring. These Pop Rocks ingredients are heated to the boiling point and the hot sugar mixture is mixed with carbon dioxide gas under high pressure (about 600 pounds per square inch or “PSI”). The process causes tiny, high-pressure bubbles of carbon dioxide gas to form in the candy.
When the hot candy mixture cools and the pressure of the gas is released, the hard candy shatters into tiny pieces of “carbonated” candy. If you look carefully at the candy with a magnifying glass, you’ll see the tiny bubbles, each containing a small amount of carbon dioxide gas under high pressure (600 PSI). When the candy melts in your mouth, the 600 PSI bubbles of gas are released with a loud popping sound. Very cool!

Pop Rocks Candy Experiment — and More

If you liked this Pop Rocks and soda experiment, you’ll love our other science experiment ideas here at Steve Spangler Science, where we aim to create experiments with that signature Steve Spangler Science WOW factor that we’re known for. Take advantage of all that Steve Spangler Science has to offer. Check out our online experiment library, gather your lab supplies and get ready to learn more about force and motion, food science and color science. Each experiment allows kids to get hands-on and learn through doing. Get them excited: they’ll soon be asking questions and being inquisitive about the world around them. If that involves eating some Pop Rocks candy, even better!

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