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What do an egg shell, a sea shell and your arm bone have in common? Answer: They all contain calcium carbonate, a substance that makes them very hard. In this egg-speriment, you will find out how to make calcium carbonate disappear! Question: How can you get an egg shell off without breaking the egg? Materials:
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| Procedure: 1. Being careful not to crack the eggs, carefully place them in the jar or glass. 2. Pour enough vinegar over the eggs until they are completely covered (if 500 mL of vinegar is not enough, add more until covered). |
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3. Watch the eggs for about
five minutes. Observe the bubbles of gas that |
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What Happened - and Why? Egg shells contain something called "calcium carbonate." This is what makes them hard. Vinegar is an acid known as acetic acid. When calcium carbonate (the shell) and acetic acid (the vinegar) combine, a chemical reaction takes place and carbon dioxide (a gas) is released. This is what the bubbles are made of. The chemical reaction keeps happening until all of the carbon in the shell is used up - this takes about a day. When you take the eggs out of the vinegar, they are soft because all of the carbon escaped out of the shell in those little bubbles. The egg still stays together
and doesn't fall apart because it has an "invisible membrane on
the surface of it which does not react with the vinegar. |
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Shell-less eggs or "naked eggs" are amazing. Amaze your friends or family even more when you change the shape and size of "naked eggs." Don't believe it? Try it! Question: Can an egg change its size or shape? Materials:
Procedure: 1. Fill one jar or glass
about half-full with clear corn syrup and fill the other with water. Both eggs will look very different than any eggs you've ever seen before. What you see is due to a process called osmosis. Osmosis is a process that equalizes - or makes the concentration of water on both sides of the egg membrane the same. (The membrane is an invisible covering between the egg shell and the egg itself.) Since corn syrup has a lower
concentration of water than an egg does, the water in the egg moved
out of the egg causing the egg to "shrink." The egg in the
water expanded or got bigger, because there was a greater concentration
of water outside the egg membrane, which caused the water to move into
the egg. That's why this egg is bigger than the egg you started with
in the first "Naked Egg" egg-speriment. |
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| Source: Adapted from http://www.kidzone.ws/science/egg.htm | |
| Click here for a printable PDF document of this egg-speriment - 84KB (Adobe Reader required). | |
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