Explore what happens when you mix oil and water, and food coloring and learn about liquid density. A simple oil and water science experiment for kids to enjoy! There are tons of ways to have fun with science all year round!
Oil and Water Experiment
Grab this free printable information guide on density to add to your project. Plus, it also comes with our best science practice sheets to share. You can find more easy density experiments here!
Supplies:
- Baby oil
- Water
- Large cup
- Small cups
- Food coloring
- Dropper
- Spoon
- Toy fish (optional)
Instructions:
STEP 1. Fill the small cups with water.
STEP 2. Add 2 to 3 drops of food coloring to each cup. Stir with spoon. Notice what happens to the food coloring.
STEP 3. Next fill the larger cup with baby oil. You don’t need to fill it too full – halfway is fine.
STEP 4. Fill the dropper with the colored water. Slowly drop the colored water into the cup of oil and watch what happens! Add the toy fish for some fun play!
Extend the activity by adding additional color drops such as yellow and watch the colors mix! The colors may start to mix at the bottom of the cup for a cool effect.
💡 For older students, here’s a list of more oil and water experiments.
Oil and Water Experiment Explanation
Did you notice the oil and water separated even when you tried to mix them together? Oil and water don’t mix because they have different properties.
Water molecules are polar (they have a slight electric charge), while oil molecules are nonpolar. This causes them to stay separate, with oil floating on top because it’s less dense (or heavy) than water.
Food coloring is made of water-based dyes, so when you add drops to the oil and water mixture, the coloring sinks through the oil and only mixes with the water. This is because food coloring is polar like water, so it dissolves in water but not in oil.
💡 See here for a more detailed explanation of why oil and water don’t mix.
Explore More Oil and Water Experiments
Want to see how you can mix oil and water using an emulsifier? Check out our salad dressing activity.
How about a classic homemade lava lamp with oil, water, and alka seltzer tablets!
Making a density tower is another great way to observe how not all liquids weigh the same.
💡 Explore more density experiments [here].
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