Water Cycle Activity
Heavy Water

In this water cycle activity you will be learning about some of the properties of water. You know that ice cubes float in water. In this intriguing activity, can you guess what happens when an ice cube floating in oil begins to melt?

Water cycle activity, Heavy Water, Photo by Myrna Martin


  • Red, blue or green food coloring
  • Ice cube tray
  • Bottle of salad oil
  • Plastic container


  1. Mix food coloring with water so that it turns a dark color.
  2. Freeze the colored water in an ice cube tray overnight.
  3. The next day pour the salad oil into a container that is deep enough to float an ice cube.
  4. The ice cube should be at least 3 inches from the bottom.
  5. Watch what happens as the ice cube melts for about 5 minutes!

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Science behind the activity

The ice cube floats in the oil because water expands when it freezes and becomes lighter than the salad oil. As the ice cube melts and turns into a liquid it contracts.

The water becomes heavier than the salad oil forming round balls of water suspended in the salad oil as it drifts to the bottom of the container.

The water forms small balls of liquid because the water molecules are attracted to each other and not the oil. This causes surface tension to form on the outside of the water molecules. The shape they form, a ball, is the most compact shape it can form as it drifts down through the oil.

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Water Cycle Activity, Heavy Water Watch what happens when ice cubes floating in a container begin to melt!

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