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Make Apple Seeds Dance
In this science experiment, kids will explore acid-base chemical reactions and buoyancy as they turn apple seeds into diving subs.
The bubbles in this experiment come from a chemical reaction between an acid (vinegar) and a base (baking soda).
Apple seeds do not normally float. When an object can float, we say it is “buoyant.” Apple seeds are not buoyant in vinegar, so they sink right to the bottom. But when the air bubbles begin to stick to the outside of the seeds, they act like little balloons that pull the seeds to the surface. When the bubbles pop, the seeds sink again, and the process repeats itself. This same principle is used to make submarines sink and float in the ocean!
Materials
- Apple seeds - 3-5 per student
- Clear cup or glass - 1 per student
- Vinegar - 1 cup per student
- Baking soda - 1 teaspoon per student
Instructions
Fill the your clear cup or glass about 2/3 full with vinegar.
Drop in the apple seeds; they will sink to the bottom.
Add about 1 teaspoon of baking soda per cup of vinegar used and stir. (Adding more baking soda will create a big volcanic eruption! For this experiment, we are trying only to create moderate bubbling.) Bubbles should immediately form from the chemical reaction between the baking soda and vinegar, and begin to accumulate on the sides of seeds. Eventually there will be enough bubbles to pull the seeds to the surface, much like a hot air balloon can pull a basket through the sky. But when the bubbles reach the top of the vinegar they will pop, and the seeds will sink again. This cycle will repeat itself over and over until the bubbling from the reaction stops.
You can prolong the experiment by adding more baking soda when the bubbles slow down.
Extension:
When you are finished observing the raisins, make a volcano by dropping in a heaping Tablespoon of baking soda!
This experiment also works well with raisins and candy conversation hearts (the ones you see in stores around Valentine's Day).
