More Egg Experiments

Egg In A Bottle

Kids never cease to be amazed by this little trick, no matter how many times you show it to them.

What You'll Need

• 1 Hard Boiled Egg Peeled
• Boiling Water
• A Bottle with a neck slightly smaller than the egg

The Experiment

1. Set the egg on the neck of the bottle to demonstrate that the egg simply won't fit in the bottle. Tell the child that you know a trick to make that egg go down into the bottle without breaking it.

2. Remove the egg from the bottle and pour the boiling water into the bottle. Carefully roll the water around in the bottle and then pour it out.

3. Quickly put the egg back on the neck of the bottle and wait for it to get sucked down into the bottle.

The Explanation

When you put the hot water into the bottle and then poured it out, the hot water left steam behind in the bottle. The steam forces out some of the air that was already in the bottle. As the steam in the bottle cools down, it converts into tiny droplets of water. The drops of water require less space and this reduces the amount of air pressure in the bottle. The pressure on the outside of the bottle is greater than the pressure on the inside of the bottle and that is what forces the egg into the bottle.

You can remove the egg from the bottle using the same process in reverse. Hold the bottle upside down and blow into the bottle for about 30 seconds. Be sure to seal your lips around the mouth of the bottle when you do this. By blowing into the bottle, you will increase the pressure on the inside of the bottle and force the egg out.

Can You Make An Egg Float?

This experiment will be too difficult for younger kids to grasp, but school age children should be able to do this one. The idea is to demonstrate bouyancy and how the density of water affects it.

What You'll Need

• 3 Clear Drinking Glasses (identical ones are best)
• 3 Eggs
• A Tablespoon
• A Straw, popsicle stick, or stir stick
• Water
• Salt

The Experiment

1. Fill each of the glasses halfway up with water. Put one egg in each glass. Choose one of the glasses to be the control glass (Glass 1). That means that you won't do anything to it and it will give the child something to compare the other glass to.

2. Now, begin adding salt to the non-control glasses (Glass 2). Start by adding 3 tablespoons of salt to one of the glasses and gently mixing it up in the water with a stir stick. Observe what happens with the child.

3. Add 10 tablespoons of salt to the other non-control glass (Glass 3) and gently stir it up. Slowly pour water into the glass until it is full, but don't stir it.

What You Should Observe

Glass 1: This glass simulates a fresh water environment. The egg will sink to the bottom in fresh water.

Glass 2: This glass simulates a salt water environment. The egg should rise to the top of the water and float in this glass.

Glass 3: This glass shows what happens when you add fresh water to salty water. The egg should be suspended in the middle.

The Explanation

The more dense a liquid is, the greater it's bouyancy and the easier it is to float. Salt makes water more dense.

When you add fresh water to the denser salt water, it will float also. In fact you can tell exactly where the salt water and the fresh water meet in the glass by where the egg is floating.

How Strong Is An Eggshell?

Usually we think of eggshells as being pretty fragile, but this experiment shows that they are much stronger than we think.

What You'll Need

• 4 Eggshells
• Masking Tape
• Scissors
• Weights (Books, cans, or anything else that you can stack)

The Experiment

1. Wrap a piece of masking tape around the middle of each of your eggshells. Cut them in half with the scissors on the masking tape. The tape will keep the shells from cracking and let you get a flat edge on each of the shells. You'll need four halves.

2. Lay each of the four halves down on a table with the cut side down and the domed side up. Put them close together to make a square.

3. Start laying on the weights. We've done this experiment with both canned food cans and books. The easiest way we've found is to put a small book on first and then add other things on top of the book. My kids like using wooded blocks the best.

4. Keep stacking on the weights until one of the eggshells begins to crack... This can be quite exciting to the kids. Be sure to note how much weight the eggs hold - the kids will be impressed.

The Explanation

The real secret to the strength of the eggshells is their shape. Because each shell is domed, there is no single point on the shell that has to support all the weight and the weight is carried down the curved walls to the base of the shell (the flat edge). This makes them extremely strong.

Talk with your child about how to apply this idea to building construction and other elements in real life. You can also talk about other shapes that use the same basic principle to increase strength.