Grow or shrink an egg (Is it magic!?!)

  1. 2 ping pong eggs (See the writing Ping pong egg!)
  2. 2 transparent glasses or containers where at least one egg will fit
  3. A weight measure machine
  4. Some fresh water
  5. Half cup of salt

  1. At first measure the weight of each ping pong egg on the weight measure machine and then write down or record their weights.
  2. Now carefully place one ping pong egg inside each transparent container.
  3. Then Put some fresh water into the transparent jars.
  4. After that add half cup of slat in one of the transparent or glass containers.
  5. Now keep both of the ping pong eggs under observation for about 2 days.
  6. Measure the weight of the eggs and record them once a day.
Eggs in fresh and salted water
  1. The more time the ping pong egg spends in the pure or fresh water the larger and also heavier it becomes.
  2. The more time the ping pong egg spends in the salted water the smaller and also lighter it becomes.
Eggs growing and shrinking!
EXPLANATION : The ping pong eggs actually change their size and weight in a special process which is called osmosis. Osmosis is the process by which water flows from an area where there is a higher concentration or density of water to an area where there is a lower density or concentration of water. When we make a normal egg into a ping pong egg by using vinegar, the calcium in the eggshell actually dissolves. So water can pass through the membrane of a that egg . So in this experiment there are 2 liquid sources. One source is inside the egg and another source is outside the egg which is either fresh/pure water or salted water. In the transparent container with the fresh water, the density or concentration of water is higher outside the egg than inside. In this case the osmosis process causes the pure water outside to flow into the egg. This also makes the egg to grow or inflate which means the membrane now holds a higher density of liquid than before. In the transparent container containing salted water, the concentration of liquid is lower outside the egg than inside. In this case the osmosis process causes the water or liquid inside the egg to flow out of it. This makes the egg shrink or deflate which means that the membrane now holds lower density of liquid than outside the egg.

The membrane around the ping pong egg is a semipermeable membrane which means it doesn’t allow everything into the egg. But some materials such as water can easily freely flow bask and forth through the egg membrane. But the membrane is well designed to keep things like proteins and other large molecules in or out.

  1. Try this experiment with oil instead of fresh water or salted water. See if water came out of the egg. Observe if there is a layer of water on the ping pong egg shell.
  2. After the egg has grown in the fresh water, take it out of the water container and place it in another jar of maple syrup. Maple syrup has a lower water density or concentration than the inside of an egg. See if the egg shrinks. See if the density of the maple syrup changes and it becomes more runny or not?


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