by Meredith Brustlin, CMNH Educator

There are so many fun experiments that you can try using oil and water. If you’re at the grocery store and thinking about picking up one or two items for your young scientist’s “at home chemistry station” I definitely recommend a big jug of vegetable oil. It’s inexpensive, easy to find, and can be used for tons of science! 

This experiment does some simple MESS FREE oil and water mixing. I especially like this experiment because the experiment itself is quick and can be done over and over again. Some people also use these oil & water mixing bottles as sensory bottles - moving the oil back and forth and watching the gentle waves it makes can be very relaxing. Who doesn’t need a bit of extra relaxation these days? 

Here’s how to make your own:

Materials needed:

• Small jar or container with a lid that can be securely screwed on (plastic or glass--although with very young scientists you may want to go the plastic route and duct tape that lid on there, too!)
• Vegetable oil
• Food coloring

Directions:

• Fill your container halfway with water
• Pour vegetable oil in to fill up the rest of the container
  • Watch and see what happens!
• Add a drop of red or blue food coloring
  • Watch closely again! 
• Tightly secure the lid of your container
  • Optional: add some duct tape to really seal it in place

• Watch as the oil and water in your bottles become completely separate and the drop of food coloring makes its way down to the water portion of the bottle - it will take a few seconds. 
• Gently move the bottle around and watch the oil and water - they stay separate when moved gently
• SHAKE your bottle! Really shake it and watch as the water and oil temporarily mix
  • What else happens?!
• Watch closely again as the oil and water slowly separate

The Science: 

There are several different science “happenings” going on during this experiment. 

Oil & Water:

• Your scientist’s will notice that the oil and water do not mix! The oil sits on top of the water and it always will. This is because water and oil are immiscible. Basically what this means is that water molecules only want to hang out with other water molecules and the same with oil molecules. The oil sits on top because it is less dense or less heavy than the water so it happily floats on top of it. 

Primary/Secondary Colors:

• Vegetable oil is used for this experiment because it is yellow in color. If we used another kind of oil, like baby oil, you would have to purchase oil based food coloring which isn’t all that easy to find. The yellow vegetable oil automatically gives us one of our primary colors. Blue or red food coloring is added so that when you mix, you get a secondary color! 
  • There are lots of great books you can read/find videos of online to explore primary/secondary colors, check out: 
    • Mouse Paint by Ellen Stoll Walsh
    • Mix It Up by Herve Tullet
    • Monsters Love Colors by Mike Austin