Three Egg Citing Experiments

Eating an egg one day, is it your habit? Have you ever thought of an egg could aid you carrying out EXCITING experiments? It is possible! Continue to read and you will find the ways.

Cooked Egg? Raw Egg?

If your mother mixes up a cooked egg and a raw egg, how will you help her? It is not a hard job that you firstly hold the egg in position as shown in figure 1, and then spin it. The one which spins well should be the hardboiled egg (figure 2) while the wobbling one should be the raw egg (figure 3). Several trails, however, may be required.

Figure 1: An egg is being held Figure 2: A cooked egg Figure 3: A raw egg

в--‹cIris Poon, 2004 в--‹cIris Poon, 2004 в--‹cIris Poon, 2004

The Steve Spangler web site has an interesting explanation of why this happens, which is summarized as follows:

Raw egg cannot be spun because the liquid egg white and egg yolk in raw egg are free from the egg shell. When the egg shell is rotated, the liquid components inside are reluctant to move and therefore the egg cannot be spun successfully. This also explains why you feel you move backward when the car you are sitting in starts moving. You are actually reluctant to move and tend to remain in the state of rest. For the cooked egg, the solid egg white and egg yolk become stick to the egg shell. They can thus be spun together with the egg shell (Steve, 2004).

Disappearing egg shell

In this experiment, a boiled egg (with egg shell) is put into a glass of vinegar. The glass should be kept uncovered. After 24 hours, replace the glass with fresh vinegar. Observe the egg after another 24 hours. The egg shell disappeared! Try to feel the texture of egg with a spoon. The egg white and yolk are hardened.

The reason for this is that the main composition of egg shell is calcium carbonate, which react with acid (vinegar contains acetic acid) and gives out carbon dioxide and salt (Exploratorium, 2004). That is why gas bubbles are on the egg surface. That salt should have been dissolved in the vinegar, therefore you cannot observe it. The egg white and yolk are hardened because the protein is destroyed by the acid.

Bumping Egg* (Parental assistance is required)

What you need in this experiment is a boiled egg with shell removed, a match and a glass bottle with mouth slightly smaller than the diameter of egg (figure 4). Follow the procedures in figure 5.