Disappearing Shell Egg-speriment

Bird eggshells are also made from calcium carbonate. In the following experiment you will see what happens when you put an egg in vinegar.

Ages 7 and up; Download Printable PDF

You will need: 
egg
cup or jar
bowl
white vinegar
knife

Preparation
Place the egg in a cup, and cover with vinegar overnight.

After the shell dissolves, all that is left is the
membrane surrounding the yolk and white. 

Observation 
Look at the egg. Do you notice anything unusual about it? For one thing, it now floats. For another, it is probably covered with tiny bubbles. Carefully pick it up and place it in a bowl. The egg’s surface feels soft because the calcium carbonate shell has dissolved, and all that is left is an opaque white membrane. The egg looks and feels hard boiled, but if you puncture the membrane, you'll see that it is raw.

What’s Happening?
Bird eggshells are made from calcium carbonate. Acid is corrosive to calcium carbonate, so vinegar dissolves the shell. All that is left is the membrane that lines the inside of the shell. Since the egg isn’t as dense without its shell, it now floats. Air bubbles form when the dissolved carbonate from the shell reacts to form carbon dioxide gas.

More to Try 
Like eggshells, seashells are made from calcium carbonate. Try putting a seashell in vinegar and see what happens. Don’t do this with a seashell you like, however, because chances are it won’t look the same when you are done!