The Water Parfait

Volume is the amount of space something occupies. Water volume, or the space it occupies, changes depending on if water is a liquid, gas or solid.

The weight of substance’s volume is called density. The ability for something to float depends on its volume and its weight. The denser something is, the more likely it will sink. For example, warm water is less dense than cold water, so it floats on top of it.

Try this experiment to learn about density and what rises to the top!

Here’s what you need:

  • 4 empty glasses (tall)
  • Cold water
  • Hot water
  • Salt
  • Food coloring (4 different colors)

Here’s what to do:

  1. Take four glasses. Put cold salt water in the first, cold water in the second, hot salt water in the third and hot water in the fourth.
  2. Add a different color of food coloring to each glass.
  3. Take a tall glass and carefully pour the colored water from each galss into it, beginning with the cold salt water and ending with the hot water.  Be careful not to mix the layers - pouring over a spoon works well.

What happened?

The cup should have layers of hot water on the top, then hot salt water, cold water and cold salt water. This reinforces the fact that warmer water is less dense than cold water so it floats on top of it. Fresh water floats on salt water, as long as the two don’t mix.