Oil & Water – Science Experiment

Oil and water just don't mix but they do provide for some amazing hands-on science.

The Oil and Water Experiment at Steve Spangler Science 

Oil and water, like cats and dogs, just don’t mix. They do, however, provide for some amazing hands-on science oil and water experiments. Learn how to conduct the oil and water density experiment with items you likely already have at home. It’s easy! 

Why Does Oil Float on Water? 

There’s something very important about oil and water that you probably already know: oil doesn’t mix with water. That fact in science is why oil spills on the ocean float on the surface; it also explains why throwing water on a grease fire is just going to make the fire worse. Since you realize that oil and water don’t mix and never will (without some chemical help), let’s have some fun with how they repel each other. Our oil and water density experiment will allow you to observe firsthand how these two natural substances will steer clear from each other. 

Experiment Materials

Experiment Videos

Experiment

1

NOTE: Before you do this, make sure you’re working in the large tub. This effect is dramatic but the science you demonstrate can get lost in the mess you’ll be making. See the “Take It Further”  section for more ideas.

Set one of the identical containers in the tub. Fill the container to the brim with vegetable oil.

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In an identical second container also in the tub, add several drops of food coloring. The color choice is completely up to you.

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Fill the container to the brim with water.

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Set the playing card over the mouth of the container filled with vegetable oil. Hold it firmly in place. Lift the oil container, turn it upside-down, and line it up directly over the water-filled container. Set the oil in place over the container holding the water. Keep the card between the containers to let the liquids settle. Slowly and gently remove the playing card. What happens? The oil and water remain in their respective upper and lower containers.

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Now, repeat the process. (Basically, this means start over completely. See the “Take It Further” section.) This time, turn the water container upside down and place it on top of the oil-filled container. Carefully remove the card and watch what happens. The water and oil trade places! If you wait long enough, it will look almost exactly opposite of how it started, too.

How Does It Work

First of all, in this liquid density experiment you confirmed what you already k oil and water do not mix. The molecules of water simply can’t mix with the molecules of oil. Even if you try to shake up a bottle of half-oil and half-water, the oil just breaks up into smaller droplets; however, it truly doesn’t mix with the water. Also, food coloring only mixes with water. It does not color the oil at all. (If you happen to see food coloring in the oil, those are simply tiny droplets of water that are trapped in the oil.)

When you set the water container above the oil container and remove the card, the water sinks and the oil floats. They trade places! Oil floats on the surface because water is heavier than oil. (Scientists would say that water is denser than oil.) This is why the oil always stays in the top container.

Take It Further

With oil and water experiments, there really is no way to NOT make a mess with this activity. Whether you’re performing a water in oil experiment on your own, in your classroom or in front of a crowd, it really doesn’t matter — this oil and water density experiment can be pretty messy.

If you’re in a performance setting and time matters, use four identical containers; then, fill two with oil and two with colored water in advance. To be safe, do all your work in a tub and leave the container of oil on top of the water. Perform the change with the second container of water on the top in a second tub. (The comparison is good for the audience to see before you pull out the card.) When you do pull the card, the colorful swap will take place and everybody will cheer!

Now, you’re either on your own or in front of a crowd and the challenge comes when you separate the glasses. You want the oil (on top no matter what) to flow down the lower glass and into the tub. That happens when you separate the glasses — even a little bit. 

To clean up after it flows out, stir a little dish soap into the oil, pour in the colored water, swirl the tub, rinse the glasses and pour the soapy solution down a toilet. Yes, it’s a mess — but it’s all for science so it is totally worth it!

Steve Spangler Science Online Experiments

In this fun water density science experiment, you’ve learned how to separate water and oil and turn it into an amazing performance that will get ooohs and ahhhs from the audience. This experiment with oil and water will amaze your family and your friends and will turn an everyday principle of food science (and chemistry) into a learning experience. Find the best liquid density experiments online with easy-to-follow directions at Steve Spangler Science, where we present experiments with our signature WOW factor. Don’t miss our other online experiments with chemistry, biology, food science and earth science, too! Our fun experiments will keep you asking questions about the world around you.

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