Sewell's Science

The bubbles you see forming on the shell are carbon dioxide (CO2). Vinegar is an acid called acetic acid (CH3COOH).

 

Eggshells are made up of calcium carbonate (CaCO3).

 

The acetic acid in the vinegar reacts with the calcium carbonate in the eggshell to make calcium acetate plus water and carbon dioxide that you see as bubbles on the surface of the shell.

The chemical equation for the reaction is:

 

2 CH3COOH + CaCO3 = Ca(CH3COO)2 + H2O + CO2

 

Acetic acid + Calcium carbonate = Calcium acetate + Water + Carbon dioxide

 

When you shine a light through the egg it looks translucent this is because the hard, outside shell has gone. The only part that is keeping the egg together is the thin membrane called a semipermeable membrane.

 

Because the contents of the egg have already been blown out, the membrane is just full of air. You can fold it up and the air will sneak out the tiny hole in the membrane that you used to empty it.

 

As you gently toss the “folded egg” around and bounce it on your hand, the air will re-enter the membrane, inflating it back into its original shape and volume.

 

And remember don’t try this at home, try it a friend’s home!