Eggsperiment

Have you ever wondered what the cells inside of your body look like? Doing some experiments with chicken eggs can give you a pretty good idea. This is a great experiment to do in conjunction with a human biology unit or for a science project at school!

We will be using vinegar to eat away the shell of an egg and then observing what is hidden inside. We'll also learn a good deal about osmosis. Ready? Let's go.

Total Time: Several days to completion
Safety Concerns: Always make sure to wash your hands after handling raw eggs. Be careful not to get any vinegar in your eyes either!

Materials You Need:

Part I
2 eggs
2 cups of vinegar (white or cider)

Part II
Food Coloring
1 cup of corn syrup
1 cup of water

Directions, Part I:

• Put each egg in a cup of vinegar. The egg will float at the top and a bit will hover above the surface, which is just fine.
• Place your cups in the refrigerator for a couple of days, checking every 12 hours or so to see when the shell is completely gone. What do you see?

You should observe bubbles on the surface of the egg almost immediately. Those bubbles are carbon dioxide gas forming due to the reaction between vinegar (which is acidic) and the calcium carbonate egg shells. Over time the vinegar will completely dissolve the entire egg shell.

What does it feel like? What does it look like?

Now for some fun with your shell-less eggs! Carl Nelson, over at Imagination Station Toledo, wrote a whole article about different experiments to try with what he calls "naked eggs". One experiment that we did brilliantly illustrates the principle of osmosis.

The membrane of a cell (in this case, the egg) is semipermeable, meaning that small particles can go in and out of the cell while large particles stay out. Water and other nutrients are small enough to travel in and out of the cell. When the concentration of water in the cell is different than the concentration of water outside of the cell, the water will move either in or out of the cell in order to balance the concentration inside and out. This is called osmosis.

The next part of our experiment will show you how to make your naked egg get big and plump and also how to make your egg shrivel, depending on what liquid you immerse your egg in next. Get ready to watch osmosis happen!

Directions, Part II:

• Fill one cup with water. Add a few drops of food coloring. (We did red.) Put one shell-less egg in your cup.
• Fill another cup with corn syrup. Add a few drops of food coloring and stir it around. (We did green.) Put the other shell-less egg in that cup.
• Put both cups back in the refrigerator and wait for a day or two. Then pull them each out and note what you see.

The egg that was in the the water should be big and beautiful. This is because it has absorbed water from the cup. You can even see how the food coloring has made it through the membrane to color your egg! An egg is about 90% water so when it is immersed in 100% water, some of that water will go inside of the egg to try to equalize the concentration.

The egg in the corn syrup is a different matter. Corn syrup has a very low concentration of water in it so some of the water from the inside of the egg will travel through the membrane to the corn syrup. This makes the egg shrivel up and get smaller.

You can see from our experiment that the egg turned green from the corn syrup. This shows that water is constantly moving across the membrane, in and out of the egg. Overall, though, the egg loses water through osmosis because the concentration of water is lower on the outside than it is on the inside of the egg.

Next time I want to try putting the shriveled egg into a cup of water to see if it will swell up again. What do you think will happen?

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Thanks, Kitchen Pantry Scientist!