If you soak chicken bones in acetic acid (distilled vinegar), you’ll get rubbery bones that are soft and pliable as the vinegar reacts with the calcium in the bones. This happens with older folks when they lose more calcium than they can replace in their bones, and the bones become brittle and easier to break. Scientists have discovered calcium is replaced more quickly in bodies that exercise and eating calcium rich foods, like green vegetables.


This is actually two experiments in one – here’s what you need to do:


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Materials:


  • hard boiled egg
  • glass or clean jar
  • distilled white vinegar


Download Student Worksheet & Exercises


When you first plop the egg in the vinegar, do you notice the tiny bubbles? The acetic acid (distilled vinegar) reacts with the calcium carbonate in the eggshell, and you may even notice a color change over a couple of days.


How high does your egg bounce? Does it matter how long you leave it in the vinegar for?


The second part of this experiment is to try this again, but now use a raw egg (wash your hands after handling your egg due to salmonella!) You’ll get a difference result – the eggshell will become flexible, but don’t bounce them.


Exercises


  1. Describe what the eggshell looked like before the reaction.
  2. Describe the acetic acid
  3. The product you witnessed in this chemical reaction was carbon dioxide, a colorless, odorless gas. How can you tell there really was a chemical reaction?
  4. Why did the egg turn to “rubber?”

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2 Responses to “Rubber Eggs”

  1. For the vinegar experiment where you remove the outer shell of an egg, you should use a raw egg, not a hardboiled one. The acetic acid in the vinegar reacts with the calcium carbonate in the eggshell, dissolving it and leaving behind the soft, flexible membrane. This creates a “naked egg” that’s squishy, translucent, and fun to gently bounce or examine. Using a hardboiled egg won’t produce the same effect, since the inside is solid and the overall result isn’t as flexible or visually interesting. A raw egg gives the best demonstration of the chemical reaction and makes the experiment more engaging.

  2. Cooked or uncooked chicken bones? Or either-or?