An Interesting experiment- Soft Shelled Egg

What you need:

1 egg (hard boiled is less messy if you accidentally break it, but you can use a raw one)
1 cup vinegar
clear jar or glass
Optional:  Soft Shelled Eggs Printable Activity Sheet

    







Directions:

Pour 1 cup of vinegar into jar
  
Add the egg

Record what you see (bubbles rising from the egg)

Leave the egg in the vinegar for one day.

Remove the egg and feel it.

Record your observations (the egg shell will be soft)


What happened:

Eggs contain something called "calcium carbonate".  This is what makes them hard.

Vinegar is an acid known as acetic acid.

When calcium carbonate (the egg) and acetic acid (the vinegar) combine, a chemical reaction takes place and carbon dioxide (a gas) is released.  This is what the bubbles are made of.

The chemical reaction keeps happening until all of the carbon in the egg is used up -- it takes about a day.

When you take the egg out of the vinegar it's soft because all of the carbon floated out of the egg in those little bubbles.

NOW TRY THIS:

Leave the same egg sitting out on the table for another day.

Now feel it again.

It's hard!

The calcium left in the egg shell stole the carbon back from the carbon dioxide that's in the air we breath.

- OR -

If you were using a raw egg, once the shell has softened, you can place the egg in water and it'll absorb and expand via osmosis until the shell finally bursts.  (Thanks to James for sharing this tip!)
OR THIS:  (KNOTTED BONES)

What makes our bones hard?  That's right!  Calcium carbonate -- the same thing that made the egg shells hard.

Optional:  Knotted Bones Printable Activity Sheet
Take some thin chicken bones and drop them in vinegar for a day.  Take them out and they'll be soft just like the egg shells were.

Now you can tie them in a knot, just like a piece of string.