Egg-cellent Egg-speriments, by John Cowens

Make eggs squeeze through tight spaces and bounce into the air, with a little help from science

Welcome to another exciting school year! One way to help students improve in science is to use the scientific method – a process of thinking through possible solutions to a problem and testing each one to find the best solution. For the steps of the scientific method click here and try applying them to these experiments.

Egg in a bottle
This experiment deals with high and low pressure. It's guaranteed to fool everyone. Does the egg really get sucked into the bottle?

Materials:

• three peeled hard-boiled eggs
• one glass milk bottle or equivalent (opening must be slightly smaller than the egg)
• vegetable oil
• wooden matches
• sheet of paper
• safety goggles

Procedure:

1. Tear a piece of paper to approximately 1" x 4" (2.5 cm x 10cm).

2. Smear vegetable oil on the inside of the bottle's opening and the egg.

3. Light the small piece of paper, drop it into the bottle and immediately place the egg on the bottle's opening.

4. Observe the egg going into the bottle!

Note: If your school doesn't allow you to light a match in class, then pour hot water into the bottle and swish it around for 30 seconds. Pour the water out and immediately place the hard-boiled egg on the bottle's opening. Thunk! The egg slides into the bottle.

What happened?
When the paper burned inside the bottle, it consumed the oxygen and created low air pressure – a vacuum – in the bottle. The air pressure outside of the bottle was much greater, and it pushed the egg through the bottle's opening.

If you used hot water instead of burning the paper, the warmed air inside the bottle was less dense than the cooler air outside the bottle. The difference in air pressure caused the egg to be pushed into the bottle.

Getting the egg out of the bottle

1. Smear vegetable oil inside the neck and rim of the bottle.

2. Hold the bottle upside down so the egg is lodged in the opening.

3. Put on safety goggles, tilt your head back, seal the opening of the bottle with your lips, and BLOW hard.

4. Quickly release your mouth from the bottle. WARNING! The burnt paper may get into your mouth or on your face. The egg will be pushed out of the bottle.

What happened?
Blowing into the bottle created greater air pressure inside the bottle than outside of it, which pushes the egg out.

Extension
Light a small piece of paper and put it in the bottle. Place on top of the bottle's opening a water balloon slightly larger than the opening. Grab the valve of the balloon and try to prevent it from going into the bottle. Watch out, the balloon may break!

To get the balloon out of the bottle, insert a straw into the bottle and pull the balloon. The balloon will slide out with little resistance. Why?

Bouncing eggs
If a raw egg is placed in a container of vinegar for two or three days, the acetic acid will dissolve the eggshell, make the egg feel rubbery and allow it to survive a drop from a height of four to five inches (10.16 – 12.7 cm). In fact, the egg may bounce!

Materials:

• uncooked chicken eggs
• vinegar
• plastic spoon
• clear plastic cups
• safety goggles

Procedure:

1. Each student (or each group of students) places a raw egg (shell still intact) into a clear plastic container.

2. Completely cover the egg with vinegar.

3. Observe the containers for two or three days. Record the results of the chemical reaction. How much of the eggs' shells have disappeared?

4. Very carefully remove the eggs from the vinegar with a plastic spoon. (There may a be thick, waxy film on the egg.) At this time, the liquid inside the egg is behaving the same way air behaves inside a ball.

5. Put on safety goggles. While holding an egg with the plastic spoon, raise the egg to a height of four or five inches (10.16 – 12.7 cm) and release it onto a hard surface, such as a desk. Did the egg bounce? How high?

6. Record how many times each egg was dropped before it broke.

Extensions

• Place a boiled egg into a glass of vinegar. Will the shell dissolve?

• Will a brown eggshell react differently to acetic acid?

• Place a piece of chalk into a glass of vinegar and observe it for several days.

Useful resource
Bouncing Eggs: Amazing Science Activities You Can Do At Home, by William R. Wellnitz (McGraw-Hill/Contemporary Books, 1999, ASIN: 0-071-34383-0).

John Cowens has taught for 26 years. He currently teaches sixth grade at Fleming Middle School in Grants Pass, OR.