Gas Law Application

What are Pop Rocks?

Pop Rocks is a carbonated candy that includes the ingredients sugar, lactose, corn syrup, and flavoring. They are kind of like regular hard candy, but when you eat them they pop and fizz when they dissolves in your mouth.


Pop Rocks Inc. is based in Atlanta GA. The first concept of Pop Rocks was created in 1956 by Food Chemist William A. Mitchell who worked for General Foods. The candy first hit the stores in 1975 then later in 1983 the product was temporally withdrawn from the store shelves because of the "Exploding kid" rumors but a few years later they were up on the shelves again.

The "Exploding Kid"

It was said that if you drank Cola and ate Pop Rocks your stomach would explode. Well there was the rumor that a kid did this and died because his stomach exploded. It is false but it alarmed many people and the Food and Drug Administration opened a hotline to assure parents that-that would not happen.
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How are they made?

Pop Rocks are made just like regular candy but when the ingredients turn into a syrup they expose it to pressurized Carbon Dioxide gas at about 600 psi (pounds per square inch) and allow it to cool. Doing this causes tiny bubbles to be trapped in the candy. Inside the bubbles is the Carbon Dioxide gas.

How do they work?

When you put Pop Rocks in your mouth the candy starts to dissolve. When this happens the carbon dioxide gas is released making the pop that the candy is famous for.
Pop Rocks MythBuster - Cool Science Experiment

Gas Law

Combined gas law is in play here. The variables are pressure (p), volume (V), and temperature (T). We know that the pressure is changing because we feel the pop. Also the volume is changing from the contained area of the gas to our mouth. Then the temperature is changing from when it is out of our mouth to the inside of our mouth.

The equation for the Combined Gas Law is p1V1/T1=p2V2/T2.