Can You Make An Egg Float? Density Science Experiments

Look at the pictures below.  Notice how the egg sinks in the first liquid and floats in the second liquid.  The egg has the same volume and mass in both liquids.  Something is different about the liquids. 

What do you think is different about the two liquids?

Long ago Greek mathematician Archimedes discovered why things float.  Legend has it he discovered it while taking a bath.  If you fill the bathtub too full it will overflow when you get in.  Why is that?  Water has to move out of the way to make room for you in the tub.  Archimedes discovered the weight of the object determines if the object will sink or float.  If the object being placed in the water weighs more than the amount of water being displaced it will sink.  We sink to the bottom in the bathtub.  We weigh more than the amount of water being displaced.  If you place a sponge in the tub it will most likely float.  This is because the weight of the sponge is less than the weight of the water being displaced. 

In the above pictures, we can say the egg sinks because it weighs more than the amount of liquid displaced.  The egg floats in the second liquid because it weighs less than the amount of liquid displaced.  The second liquid must contain more stuff in it than the first liquid. 

Directions to Make an Egg Float

Supplies

Tall glass

Water

Salt

Raw Egg

Spoon

Bowl to Hold the Egg

Teaspoon

1.  Fill the tall glass with water.

2.  Using the spoon carefully place the egg in the water.  It should sink.

3.  Carefully take the egg out.

4.  Add 1 teaspoon of salt to the water and stir until it is completely dissolved.

5.  Place the egg back into the water.  Observe what happens.  Is it floating?  Did it change at all?

6.  Take the egg back out.  Add another teaspoon of salt.  Stir until it is completely dissolved.  

7.  Place the egg back in and observe its' height in the saltwater.  Is it floating at the top yet?

8.  Keep taking the egg out and adding more salt until the egg is floating in the water.  

Reflection

As we added more salt the water began to get heavier.  It contained more stuff(salt).  Once the amount of water displaced weighed more than the egg, the egg floated to the top.  The water became denser than the egg.

Take It Up A Notch

Expand your knowledge of density by performing this experiment with regular and diet soda.  What difference will that make?  This is a fun and exciting classroom study that includes a formal investigation, further exploration, and STEM challenge.  We changed the salt to sugar to learn the difference between regular and diet soda.  

SHOP THIS POST