The Accidental Scientist: Science of Cooking Exploratorium
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activity: Experimenting with Naked Eggs
Dissolve the eggshell—without breaking the membrane that contains the egg. Then use your naked egg to experiment with osmosis, the movement of water across a membrane.

   
What Do I Need? .
at least 2 naked eggs  
containers large enough to hold a single egg and some liquid (coffee mugs or tumblers work fine)
corn syrup  
water
a big spoon  
   
What Do I Do?

 

1. Put one of your shell-less eggs into a small container and add enough corn syrup to cover the egg. Put another egg in a small container and add enough water to cover the egg. Put both eggs in your refrigerator for 24 hours.

2. After 24 hours, take a look at your eggs. What’s happened?

   
Whats Going On?  

The egg that was in the water is plump and firm. The egg that was in the corn syrup is shriveled and flabby.

After you dissolve the eggshell, the egg is surrounded by a membrane. (Actually, it’s two membranes, but they are held tightly together.) This membrane is selectively permeable—which means it lets some molecules move through it and blocks other molecules.

Water moves through the membrane easily. Bigger molecules—like the sugar molecules in the corn syrup—don’t pass through the membrane.

When you put a naked egg in corn syrup, you are creating a situation where the egg membrane separates two solutions with different concentrations of water. The egg white is about 90% water; corn syrup is about 25% water. In this situation, random movements of water molecules cause them to move from the side of the membrane where they are more abundant to the side where they are less abundant. So water migrates from inside the egg to outside the egg, leaving the egg limp and flabby.

   
What Else Can I Try? .

• Can you think of a way to take that flabby egg and make it plump again? Here’s what we did.


Experiment with putting naked eggs into other solutions. What happens if you put the egg into water colored with food coloring? Or salty water? Experiment and see. Carefully lift the flabby egg from the corn syrup and place it into a container of water. Leave the egg in the water for 24 hours. The water will migrate from the side of the membrane where water molecules are abundant (outside the egg) to the side where water molecules are less abundant. After 24 hours, the egg will be plump again.

Share your results.

 

 

 

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