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The Disappearing Eggshell

ECS - Grade 4


10 minutes, and overnight preparation


  • fresh egg
  • vinegar
  • bowl


Soak a raw egg in vinegar (to take the calcium out of the eggshell). It will feel like rubber and you will be able to see through to the inside. (Leave the vinegar to cover the egg overnight). Discuss what happened.


The shell of the egg is made mostly of calcium carbonate (like chalk). Vinegar dissolves the calcium in the shell. The bubbles you saw when you first put the egg in the vinegar was caused by the gas that is created as a side-effect. Vinegar has, among other things, a chemical called Acetic Acid (about 3% of it is acetic acid). Egg shells contain calcium carbonate. Calcium carbonate in the egg shell reacts with vinegar to form carbon dioxide (can be seen as bubbles in the vinegar).

Calcium Carbonate: CaCO3
Acetic Acid: CH2COOH
The reaction is: CaCO3 + CH2COOH → Ca (in the form of a salt) + H2O + 2 CO2

See Also:

farm/activities/disappearing_eggshell.txt · Last modified: 2020-05-09 15:02 by