Before you get ready for a delicious scramble or omelet, add a bit of science to your morning routine! Do you know why some things float and other things don't? In this experiment, you'll use eggs (and a few scoops of salt) to study the science of floating.
Will an egg float better in salt water or fresh water?
- 2 clear containers
- Measuring spoons
- Stirring spoon
- 2 raw eggs
- To begin your floating eggs experiment, fill your two containers with water. Make sure the amounts are equal. When you're doing a comparing experiment like this, all the variables, or factors that make up the project, should be the same -- except one (in this case, salt water instead of fresh water).
- Use the measuring spoons to pour seven tablespoons of salt in the first container of water. Do not put any salt in the second container.
- Stir the container of water until the salt is completely dissolved. This may take a couple of minutes.
- Gently place one raw egg in each container.
- Watch the eggs for a few seconds. What happens?
The egg should float in salt water, but not in fresh water.
The key to this experiment is density. Density deals with how closely packed together a substance is. You can see density in your food. Imagine you have two bowls that are the same size. In one bowl, you have a salad, but the other one is full of a pot pie. Even though each bowl is filled with food, the pot pie is much denser because the ingredients are smooshed closer together than a light salad of lettuce and just a few vegetables.
In the same way, salt water is denser than fresh water. The molecules are packed tighter, and this density allows an egg to float on the water's surface. Remember that eggs have density too, but because an egg's density is less than salt water's density, you saw floating eggs. On the other hand, an egg is denser than fresh water -- that's why it sunk to the bottom of the container.
Equipped with just a bowl of salt water and a bowl of fresh water, you can test the density of all sorts of ingredients in your kitchen. Do you think a mushroom would float in both liquids? What about a block of cheese? You can even bring out the eggs again -- what do you think would happen if you tried a hard boiled egg instead of a raw one? Keep guessing and testing like a real scientist!