When you put popcorn kernels in water, they sink to the bottom. But with a little kitchen chemistry, we can make them hop to life! Adding vinegar and baking soda to the water creates a chemical reaction that releases bubbles of carbon dioxide (just like bubbles in soda!). When the gas rises up through the water, it carries the kernels with it. Then, when the bubbles pop at the surface, the kernels sink back down to the bottom until they can hitch another ride from some other bubbles.

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We chose popcorn kernels because they are dense enough to sink in water, but not so heavy that they can’t be lifted by the bubbles. If you try this with rice, you’ll find it may not work as well — rice grains are too dense and too small to catch onto bubbles. What do you think will happen if you try this with raisins? Here’s a hint: raisins are not particularly dense and they have lots of nooks and crannies for catching bubbles!



Connections with Next Generation Science Standards (NGSS)

Matter and Its Interactions 5-PS1-4

Conduct an investigation to determine whether the mixing of two or more substances results in new substances.

Experiment with acids (vinegar) and bases (baking soda) to create a new substance (carbon dioxide). The popcorn kernels help demonstrate that carbon dioxide is less dense than vinegar and baking soda. The difference in density causes the bubbles to rise up in the mixture.