Pop Rocks candy gets its popping effect from pressurized bubbles of which gas?

Pop Rocks candy gets its popping effect from pressurized bubbles of carbon dioxide gas.

During manufacture, sugar and other candy ingredients are heated into a syrup and then exposed to carbon dioxide under high pressure. As the mixture cools, tiny gas bubbles become trapped inside the hardened candy. When Pop Rocks dissolve in the mouth, the candy’s structure breaks apart and releases those bubbles, producing the characteristic crackling and popping sensation.

Carbon dioxide is the same gas used to carbonate soft drinks, although Pop Rocks contain it in a different physical form: sealed microscopic pockets inside candy rather than gas dissolved in liquid. The popping does not come from a chemical reaction between ingredients, and it is not caused by oxygen, nitrogen, or helium.

The candy’s history also explains a famous misconception. General Foods first test-marketed it in Canada in 1974 and introduced it in the United States in 1976. Persistent rumors claimed that Pop Rocks mixed with soda could cause a stomach to explode, but the story was false. The candy’s inventor and the company repeatedly explained that it was safe.