EggWiki


 * Welcome to the Egg Wiki Page!**

Have you ever seen a bouncy egg?

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Have you ever wondered why it becomes bouncy? Try this yourself!

1. Get a raw egg with its shell. 2. Measure its intial size and weight. 3. Soak egg in some transparent vinegar. Add a few drops of food dye. 4. Leave it overnight. 5. The next day, remove the egg and record your observations (new size, weight, appearance).
 * Instructions:**

For your first post, I would like you to post: 1. What were your observations of the egg before and after? Remember to include details of its weight, size and appearance. 2. Why did you think this happened?

As this is also an exercise on making good explanations, do take a while to drop in at the Assessment of Learning Page to see what makes a good explanation. Bear this in mind when answering your posts.

After you make your post, visit your group members' post and give comments on what they have written. What makes a good comment? Visit the Assessment of Learning Page to find out as well.

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Hey class, here is what we agree is the explanation for the bouncy egg:

1. Observations: Egg increased in size, egg shell floating in vinegar(bubbles observed on egg shell before this). The egg is dyed and has become "bouncy".

2. Why? Vinegar contains acetic acid. The egg shell contains calcium carbonate. When soaked, the acid reacts with the carbonate to form carbon dioxide gas. The bubbles that cling to the shell is this carbon dioxide. The vinegar at the same time also reacts with a membrane that is just beneath the shell. This reaction makes the membrane solid(much like cooking makes the egg white solidify). This membrane thus holds the liquid contents of the egg. Now that the egg shell has fully disintegrated, the water in the vinegar solution moves into the egg through the membrane through osmosis. The membrane is selectively permeable and only allows water molecules to go through. Osmosis occurs as the water potential in the vinegar solution is higher than that inside the egg. The dye molecules are larger and cannot enter, thus they remain on the membrane (thus the dyed egg). As the egg increases in size as water enters, the eleastic membrane stretches, thus the egg appears bouncy!