Pop Rocks Science

The Crush Test - Pop Rocks don't have to be mixed with a liquid to pop. Try crushing a few big pieces on the table using the back of a spoon and you'll hear the loud POP! Remember, the popping sound you hear comes from bursting the high pressure bubble of carbon dioxide. Crush a Pop Rock in your teeth and you'll hear the same cool popping sound of the gas escaping.

How Much Carbon Dioxide Gas is in a Packet of Pop Rocks? - You'll have to waste a whole package of Pop Rocks for this experiment (or you can just learn from our results). Start by pouring an entire package of Pop Rocks into an empty balloon (a 9" balloon works well). You'll also need a 12 or 16 ounce bottle of your favorite soda. Open the bottle of soda and attach the balloon, but do not let the Pop Rocks fall into the soda just yet. After the balloon is attached, you can lift up on the balloon to allow all of the Pop Rocks to fall into the soda. Predict how big the balloon will get when the Pop Rocks mix with the soda. You might be surprised by what you see. The balloon does not inflate much at all. Why?

How does it work?

How are Pop Rocks made? According to information from the manufacturer, Pop Rocks start like any other hard candy by combining sugar, lactose (milk sugar), corn syrup, and flavoring. These 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). 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 under 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!

In the experiment with the balloon, mixing Pop Rocks with soda is a physical reaction - not a chemical reaction. The soda dissolves the candy and releases the small bubble of carbon dioxide gas from the Pop Rock. Believe it or not, most of the carbon dioxide in the balloon came from the soda. Dropping Pop Rocks into soda causes some of the carbon dioxide from the soda to escape. That's the real reason why the balloon inflates.

So, will you explode if you eat Pop Rocks and drink soda? No... but you might get a pretty nice burp out of the deal.