What happens when you put an egg into a glass of water; will it sink, float, and can it do both? We found a cool experiment that will teach you about density, using just an egg, water and salt!
You’ll need
An egg
Water
1-2 cups of salt
A drinking glass
An extra cup
A spoon
Instructions
Fill the glass to about half with water.
Place an egg into the glass, and see if it sinks or floats (it should sink).
Now, stir in lots of salt. Start with a spoonful and stir until it dissolves. Keep adding spoonfuls of salt and stirring to dissolve it, until the egg floats.
Then, fill your extra cup with water from the tap. This is called fresh water, because it contains no salt. Very gently pour the fresh water into the glass containing your egg. Try not to let the fresh water mix into the salt water. If you succeed, the egg should “float” in the middle of the glass (between the fresh water on top and the salty water underneath)!
What’s happening?
The egg is denser than fresh water, so when you add the egg to the glass (before adding any salt), it will sink. When you add salt to the water, it increases the water’s density. Adding more and more salt makes it more and more dense. So eventually the water in the glass is denser than the egg. When you carefully and gently add more fresh (and less dense) water to the glass, it should float on top. The egg will “float in the middle because it is less dense than the salty water, and denser than the fresh water.
