June 27

Welcome to the Dive Deeper Weeklong Challenge


Dive Deeper Weeklong Challenge #4

The Dead Sea, a salt lake in the desert in the Middle East, has water that's nearly 10 times saltier than the ocean. For thousands of years, visitors have marveled at how easily they can float on its surface.  Plants and fish, however, can't live in the water, which explains its creepy name.  How does salt make things float?  

In this experiment, you'll discover the Dead Sea's secret and then visit the north and south poles to learn how melting ice mixes with salt water.

Supplies Needed:

  • 2 wide-mouth pint size mason jars

  • Warm tap water

  • Salt

  • 2 raw eggs

  • Spoon

Here's what to do:

Step 1:  Add 1 cup of warm tap water to each of the jars, using the markings on the side.

Step 2:  Add 3 tablespoons of salt to one jar, and stir to dissolve it.

Step 3:  Place an egg in the fresh water jar.  What happens?

Step 4:  Now place the other egg in the salt water jar.  What happens? 

What to Watch For

The egg should sink in the fresh water but float in the salt water.  With the egg floating in the salt water, add more fresh water.  The egg should start to sink.  Add just the right amount, and the egg will hover in the middle of the jar, not sinking but not floating, either.

What's Going On

Things sink or float depending on whether they are more or less dense than the liquid they are in.  Density is how heavy something is for its size.  The egg is more dense that fresh water, but less dense than salt water.  

Adding salt to the water makes the water more dense, so it support objects that might sink in fresh water.  Adding fresh water to the salt water makes it less dense, so objects start to sink.


Use the jars of fresh water and salt water for another experiment, one that demonstrates how cold and salt affect the flow of water in the oceans.  Make ice cubes from colored water and place on in each jar.  Watch what happens tot the colored water as the cubes melt.

In the fresh water, the cold melt water sinks, mixing with the water in the jar.  In the other jar, however, the dense salt water holds the cold fresh water in a layer on top.  Similar forces are at work in the oceans, especially near the Earth's two poles.