Science in the Park - Oil vs Water

This week we took a look at how oil and water just do not mix! 

Experiment 1 - Fireworks in a Jar!

In this experiment we will be making fireworks while exploring how oil and water do not mix.

Materials:

• yogurt cup (or other small container)
• food coloring
• oil
• spoon
• jar with water in it

How To: Step 1

Put a few tablespoons of oil in the cup and let the kids squirt a few drops of food coloring in it.

Step 2

Stir it up! If you skip this step - the colors will not look as pretty.

Step 3

Carefully pour the oil into the jar so that the oil stays on top.

While you watch the colors will fall through the oil and into the water where they will mix with the water and look like fireworks!

The Science:

The oil is less dense than the water - so it stays at the top of the jar. The food color is not so it slips down and then mixes with the water to create the fireworks!!

Experiment 2

In this experiment we used the principle that oil sits on top of water to paint paper!

Materials:

• Tins
• Water
• Oil
• Food coloring
• Card stock paper (the thicker paper works better)
• Fork
• Pipettes (or eye droppers or spoons if you don't have either)

How to:

• Add just a little bit of water to the bottom of the tin - you need enough to cover the whole bottom of the tray (approximately 1/8 inch).
• In a yogurt cup, mix a little oil with food coloring.  This needs to be mixed vigorously and with a fork.  Eventually (up to a few minutes) it will look like it is blended.
• Then take the pipettes and drop the oil on top of the water in whatever pattern you choose!

 

• Once the oil is added, take a piece of paper and gently lay it on top of the water.  It will soak up the oil and you will see this through the paper.
• Leave it there for 10 seconds or so and then pull it up and you will have a neat design on the paper!

The Science:

The oil sits on top of the water and so the oil mixed with food coloring is what sticks to the paper!  Oil and water do not mix because of the "like dissolves like" principle of science.  What this means is that water is a polar molecule and oil is not.  Since one is "polar" and the other is not - they cannot dissolve in one another; but rather they stay separate.  And since oil is less dense than water - it sits on top of the water. 

Experiment 3

Now that we've played with oil - let's clean it up!

Materials:

• The tin with the water and oil in it from the previous experiment
• A polyester rag

How to:

• Give the kids a small piece of polyester and challenge them to clean up the oil. 
• The polyester will do a decent job of cleaning up the oil!

The Science:

Polyester is a polypropylene - which is made of the same elements as oil (hydrogen and carbon).  These materials attract each other since they are the same; thus the polyester soaks up the oil!

Enjoy!