Liquids: Oil and Water Experiment

What happens when you mix oil and water?

Oil and water are both liquids but what happens when you mix them?

Materials:

• small recycled plastic bottle
• water
• food coloring
• oil (baby oil or vegetable oil)
• glue

Directions

• Have students predict what will happen when you pour oil and water into the same container.
• Fill half the plastic recycled bottle with water and a few drops of  food coloring to achieve the shade of color desired.
• Add cooking oil to the plastic bottle.
• Observe what happens.  (The oil will rise to the top of the bottle.)
• Put the cap on the bottle tightly!
• Shake the bottle. Can you mix the oil with the water?
• Observe what happens. (The oil will rise to the top. The water and food coloring will sink to the bottom.)
• Children may want to add a toy ocean animal to the bottle before gluing on the cap to make an underwater scene. Or they can add glitter to the bottle to make it into a lava lamp!
• Glue on the cap. (The oil can really make a mess if it leaks out of the bottle!)
• Were the students' predictions correct? Can they explain why the oil and water didn't mix?
• Ask the students if they can think of other liquids that do not mix.

Explanation

The liquids separate into 2 layers. The oil floats to the top because it is lighter or less dense than the water. The water is heavier or more dense than the oil so it sinks to the bottom. There is less matter (per cubic foot) in the oil than in the water.