What causes cavities? Sugar? Not directly. There are bacteria in the mouth that convert sugar into acid. And acids are harmful to teeth. We want to test how, but because we don’t want to destroy our teeth in the test, we need a substitute. In this experiment we are using eggshells. Like teeth, they contain calcium and are sensitive to acids. So how do acids react with eggshells – our substitute for teeth?
What causes cavities?
You will need
- Approximately 100 ml citric acid
- 1-2 empty eggshells
- Rolling pin
- Freezer bag
- Accurate scale
- Measuring cup
- Funnel with coffee filter
- Spoon
- 2 empty jam jars
Let’s get started!
1. Grind the eggshells
Put some eggshells in a freezer bag and crush the eggshells with a rolling pin. If you have a pestle and mortar, you can use that instead. The finer the powder, the better.
2. Weigh accurately
Weigh 20 g of crushed eggshells as accurately as possible in a jar on a scale.
3. Add citric acid
Add 100 ml of citric acid to the eggshells. You can use a measuring jug to measure the citric acid. Stir everything well and wait about 30 minutes.
4. Filter, dry and weigh again
Pour the contents of your glass through a coffee filter into a second glass. Now the liquid should be separated from the solid. Allow the coffee filter with the eggshells to dry completely. The best way to do this is to let everything sit overnight. Weigh the dried eggshell powder afterwards. How has the weight changed? What do you think happened?
