Calcium is a great element to study because it’s found in so many everyday items plus it’s important for our health. We talked a little about what is made of calcium and how varied it can be. Pure calcium isn’t found in naturally. Instead it’s usually part of a compound. (This was a good opportunity to review that word.) I have a round up of some good background resources we used and details about our calcium experiment.
I initially read this experiment and thought we could do it, but we didn’t get a reaction that was very easy to see. Instead, we submerged our items in cups of water and vinegar and had much better results.
We used eggshells, seashells, and teeth to test what kind of reaction calcium compounds have with an acid like vinegar. You could also use chalk, calcium tablets, or bones. Teeth and bones are both made from calcium phosphate (along with other things) while the others contain calcium carbonate.
Our first step was to compare the materials. We observed that the eggshell was much thinner than the other two and could be cracked with our hands while the seashell and tooth could not.
We used plain water as a control and tested each item in the water and then vinegar to see the difference. The eggshell initially sunk in the liquids, but after a few minutes of the acid’s work it was light enough to float! It was fun to watch it ‘dance’ around the jar.
The seashell gave a very obvious reaction and the water became cloudy. After leaving the seashell in the vinegar for a few hours, parts of the shell were completely gone. This was a really dramatic way to imagine the dangers of rising levels of ocean acidity. Mollusks are in danger if there’s too much acid!
The tooth had a much different reaction. It did not begin bubbling immediately. We discussed theories why this happened and settled on the protective enamel shielding the calcium. When we learned about teeth, we found out that prolonged exposure to acids can eventually wear down the enamel, so we figured that we would have to keep the tooth in the vinegar for several days to see the results. Since Z hasn’t lost many teeth and is still a bit attached to them, he didn’t want to completely destroy the tooth. Maybe we will try it when we have more spares.
This was a nice experiment for the kids to test their hypotheses and make guesses as to why certain results happened.
As always, thanks so much for reading and leave your favorite resources in the comments below.