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Thursday, May 20, 2010

Now Make a Shriveled Egg!

Once you have made a "rubber" egg, you can do another experiment with it. Place the egg into a jar full of corn syrup and let it sit for a few days. You will notice that all of the liquid gets drawn out of the egg, and you end up with a shriveled-up, pruney-looking egg. Why does that happen?

You're actually watching a process called osmosis (pronounced oz-MO-sis). The thin protein skin is actually a membrane, a thin film which lets some molecules pass through it, but not all molecules. When you put the egg in vinegar, the shell dissolved, but something else happened, too. The molecules in the vinegar were able to pass through the protein skin into the egg. That's why it got bigger. Now, when you place the "rubber" egg into corn syrup, the liquid inside the egg gets drawn out into the syrup, and the egg "deflates".

Osmosis is important to a lot of biology. The cells of your body are surrounded by membranes, and water and other molecules (like nutrients or waste products) can move in and out.

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