Why does popcorn pop?


Corn kernels contain a small amount of water. As a corn kernel is heated, the liquid water molecules start moving faster and eventually turn into gas. Relatively speaking, gas molecules spread out quickly and exert a high pressure. The result?
This phenomenon can be explained by the Gay-Lussac gas law, which states that as the temperature of a gas increases, so does the pressure. During the explosion, the starch granules that contain the water vapor expand enormously - turning the kernel inside out and producing a fluffy white flake. Another example of this gas law is the dangerous result of incinerating an aerosol can. As the temperature on the gas trapped within the can increases, the pressure increases also, resulting in failure of the can. (Do not try this at home!)

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