Egg Float

It changes it’s mind.

HOME  | SAFETY  | NEW | TEACHERS | PARENTS | CATEGORIES | LIST | AUTHOR

Purpose -

To examine the difference in density between fresh water and salt water

Nature - 

Demonstration

Materials - 

beaker, fresh raw egg, distilled water, salt (NaCl), stirring rod

Method - 

· Three-quarters fill the beaker with distilled water

· Place the egg into the water and note that it sinks

· Add salt and gently stir.  Repeat until the egg floats up to the surface.

Safety -

Nil

Explanation -

The density of fresh water is slightly less than an egg, therefore it sinks.  As you add salt to the water, it becomes more and more dense until it is slightly more dense than the egg, causing the egg to float. 

Notes -

This explains why you float better in the sea than you do in a freshwater swimming pool.

Ships that travel through stretches of both fresh and salt water need to be aware of this as they will float lower in the fresh water, perhaps creating a hazard when fully loaded.