Shelless Eggs

08 November 2009

Part of the show Investigating Infertility

Shelless_Egg_teaser.jpg

Credit:

Dave Ansell

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Ingredients

An egg

Vinegar

Instructions

Fill a small glass or jar with vinegar - any will work, but it might be best to use white vinegar as it is easier to see the egg.

Put an egg in, and make sure that the egg is covered with the vinegar.

Leave the egg for 24 hours.

Then have a look at the egg. Is it at all different?

Result

You should find that the shell bubbles slowly in the vinegar. After about 24 hours, there will be no shell left, and the egg will become flexible and soft.

Explanation

The eggshell is made of calcium carbonate (CaCO₃) - the same mineral as limestone. If you react a carbonate with an acid, you are left with a soluble salt, carbon-dioxide, and water. The shell slowly dissolves, producing bubbles of carbon-dioxide.

Calcium Carbonate + Acetic Acid -> Calcium Acetate + Carbon-dioxide + Water

CaCO3 + 2CH₃COOH -> Ca(CH₃COO)₂ + CO₂ + H₂O

So the only thing left holding the shell together is the membrane which keeps the liquid in the egg, which is flexible and stretchy, so the egg is flexible and squashy.