Homeschool Chemistry: Decalcification and Osmosis

Homeschool Chemistry: Osmosis and Eggs

Step 1: Decalcify two raw eggs by submerging them in white vinegar in clear jars or cups for at least 24 hours until the eggshell has completely dissolved.

Step 2: Carefully rinse the eggs and empty and rinse out your soaking jars/cups.

Step 3: Label your jars/cups, one with “corn syrup” and the other with “water.”

Step 4: Gently set your decalcified eggs in the jars.

Step 5: Cover each egg with the substance indicated on the label (light corn syrup or water).

Step 6: Watch and enjoy. You’ll see results within a couple of hours, but longer will give a more dramatic effect. The eggs in the photo above had been soaking for about 36 hours.

What’s happening?

The water on either side of the egg’s membrane is trying to reach equilibrium. In the jar with the water, there is more water outside the membrane than inside, so the water moves through the membrane into the egg. In the jar with the corn syrup, there is more water inside the egg than outside, so the water moves out of the egg’s membrane and into the corn syrup.

For more fun…

  • Place the water-logged egg in corn syrup and the corn syrup egg into water and watch osmosis reverse.

OR

  • Put a few drops of food coloring into the water jar before adding the decalcified egg. After 24 hours or so, carefully pierce the membrane of the egg to see if the food coloring passed into the inside of the egg.

These are raw eggs so, you know, wash your hands and stuff.

(We got this experiment from Adventures with Atoms and Molecules, Book II, by Robert C. Mebane and Thomas R. Rybolt. It’s out of print, but you can find it at your library or at used book sellers.)

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