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National Chemistry Week - Experiments - The Disappearing Egg Shell

The Aim:

to remove the shell from an egg without breaking the egg

What you will need:

  • 1 glass jar
  • 1 hard-boiled egg (A raw egg can be used but it can be messy if it accidentally bursts.)
  • 250 mL (1 cup) of vinegar

What to do:

  1. Place the egg in the jar.

  2. Cover the egg with vinegar.

  3. Encourage the class to make observations immediately and 24 hours later.

[IMAGE OF AN EGG INSIDE A BEEKER FULL OF 
VINEGAR]

Bubbles will immediately form on the surface of the egg and will increase in number over time. The bubbles are carbon dioxide gas. After 24 hours the shell is gone. The membrane of the egg remains. The chemical name of vinegar is acetic acid and egg shells are made up of calcium carbonate. There is a chemical reaction between the vinegar and the shell. This is what causes the bubbles to form initially and what causes the shell to disappear.

Allowing the egg to react with the carbon dioxide in the air will cause the egg to harden again. Chalk is also made up of calcium carbonate. What would happen to a piece of chalk if it was placed in vinegar?

For other chemical reactions with an acid see GREEN PENNIES, BONES IN KNOTS and THE ERUPTING VOLCANO.

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