Egg in Vinegar: A Dental Health Activity

Egg that has been soaked in vinegar, being held up to a light
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The egg in vinegar experiment can be used as followup or in conjunction with the Egg in Soda Experiment as a way to show your child how acid interacts with calcium to cause tooth decay. Of course, putting an egg in vinegar isn't exactly the same as not brushing your teeth, but the chemical reaction caused by the two substances interacting is very similar to what happens between the acid in your child's mouth and their teeth.

Materials

  • hard boiled eggs
  • a clear plastic cup
  • vinegar
  • 48 hours

Preparation Lesson

Let your child examine a hard boiled egg, even letting them smash and remove the shell if they wants. Ask them to run her tongue over their teeth and/or look at them in the mirror.

If your child doesn't already know that the hard outside of their teeth is called enamel, tell them about enamel and how it protects their teeth. Then ask:

  • What does the shell do for the egg? (protects the soft inside, etc.)
  • Does that remind you at all of your teeth?
  • Do you remember what the soft inside of your teeth is called? (dentin)?
  • Why do you think your teeth are covered in enamel?
  • What would happen if the enamel was damaged or had holes in it?

Forming Hypotheses

Tell your child you're going to leave the egg in a cup of vinegar for a few days and observe what happens to it. Help them come up with a hypothesis about what they expect to see during the experiment.

Their hypothesis may be something along the lines of "the vinegar will eat the eggshell," but if they don't propose a hypothesis that fits the end result, that's OK. That's the whole point of the scientific method—to see if what you think will happen, happens and why or why not.

Perform the Experiment

  1. Place the hard-boiled egg in a clear cup or jar and fill it with white vinegar.
  2. Cover the top of the container. Explain to your child that covering the cup is sort of like leaving her mouth closed without brushing their teeth.
  3. Observe the egg on day one. The egg should be covered in bubbles.
  4. Continue to observe the egg for another day or two.
  5. Remove the cover from the container and drain the vinegar. Allow your child to touch the egg. The shell should be soft and pitted, if not completely dissolved.

What Happened

The bubbles you saw during the experiment are carbon dioxide, a gas that is released during the chemical reaction between the acetic acid (vinegar) and calcium carbonate of the eggshell. The acid breaks down the calcium and essentially eats away at the eggshell.

Connection to Dental Health

Your child may wonder how an egg in vinegar has anything to do with their teeth. Though it doesn't happen as quickly as the reaction between the egg and vinegar, there's a similar reaction that happens in your child's mouth.

The bacteria that live in her mouth stick to the hard surfaces of their teeth. Some of these bacteria create acids when they are combined with sugar in foods and beverages they consume. These acids can break down the enamel of their teeth if they don't brush often and be careful about how the number of sweets they eat.

Note: This experiment can be very upsetting to some children. Be certain to reassure your child that their teeth won't be "eaten" by acid if they forget to brush once in a while.