"Hello, and welcome back to our weekly science experiment. I gotta say, this week was the coolest so far, and I have a feeling it will be hard to top."
How was that for a teaser? A bit over the top? Maybe so, but I really do think that I can deliver on the claim, because Science Experiment #4 was awesome. It was called "How To Make A Naked Egg" and while doing the experiment we learned how to dissolve the shell of an egg without breaking the egg AND we learned a new science word: osmosis.
The experiment began by putting raw eggs into glasses and then covering (or mostly covering if the eggs float a bit) them with white vinegar.
Very soon bubbles began to form because the acidic vinegar was beginning to dissolve the calcium carbonate shell. (Check the link above for all the technical/chemical details if you want).
After twenty-four hours there was quite a froth on top of the vinegar and the shell was visibly changing, but it wasn't completely dissolved, so we dumped out the old vinegar and refilled the glasses with fresh stuff.
At the end of forty-eight hours the shell was totally gone, but the egg remained intact inside the membrane. We could carefully hold the egg and squish it a bit. We also realized that the egg had actually gotten bigger. This is where the "osmosis" word comes in. The eggshell and membrane are permeable, so the liquid outside the egg (high concentration) moved through the membrane and inside the egg (lower concentration) and made the egg expand.
It's hard to see in this photo, but we could also see the yolk and other structures floating around inside the egg.
After handling and examining the eggs for a while Ian wanted to see how easy it was to break them. If we held them very close to the bottom of the bowl and let go the egg actually bounced instead of popping, but more then an inch drop was too much. It also didn't take much of a poke to break the membrane.
At this point Ian had fun just jabbing at and pulling apart the eggs. He handled the outer membrane and then discovered that the yoke also had a separate membrane. I was pleased to find out that a raw egg left near a sunny window soaking in vinegar for three days did not stink when it broke open.
And that is what I call a successful science experiment.
Happy experimenting with food everyone!