Mixing Oil & Water Science Experiment

Have you ever heard the saying, “Oil and water don’t mix”? For this easy science experiment, we observe exactly what does happens when we mix oil and water, then we’ll add another item to the mix to see how it changes!

With only a few common kitchen items, kids can explore density and the reaction of adding an emulsifier (dish soap) to the experiment. A printable instruction sheet with a materials list, demonstration video, and a simple scientific explanation are included.

JUMP TO SECTION: Instructions | Video Tutorial | How it Works

Supplies Needed

• Glass Jar with a lid (a pint canning jar works great)
• 1 cup Water
• Food Coloring
• 1 cup Oil (we used vegetable oil)
• 2 teaspoons Dish Soap

Mixing Oil & Water Science Experiment Instructions

Step 1 – Start by filling the jar with 1 cup of water.

Step 2 – Add a few drops of food coloring to the water and stir until combined. Make some observations about the water. What happened when the food coloring was added? Was it easy to mix the food coloring into the water? Does the food coloring stay mixed with the water? What do you think will happen when we pour the oil into the jar? Write down your hypothesis (prediction) and then follow the steps below.

Step 3 – Next pour 1 cup of oil into the jar. Make a few observations. Does the oil behave the same was as the food coloring did when you added it to the water?

Step 4 – Securely tighten the lid on the jar and shake it for 15-20 seconds.

Step 5 – Set the jar down and watch the jar for a couple of minutes. Observe what happens to the oil and the water and write down your findings. Did the oil and water stay mixed together? Was your hypothesis correct? Do you think there is anything else that can be added to the jar to prevent the oil and water from separating?

Step 6 – Next, take the lid off the jar and squirt in 1-2 teaspoons of dish soap.

Step 7 – Tighten the lid back on the jar and shake again for another 15-20 seconds.

Step 8 – Set the jar down and watch the liquid for a minute or two. Observe what happens to the oil and the water now that the dish soap has been added to the mix. Write down your findings. Did the oil and water stay mixed together this time? Do you know why adding the dish soap preventing the oil and water from separating? Find out the answer in the how does this experiment work section below.

Video Tutorial

Mixing Oil & Water Science Experiment Video Step by Step Instructions

How Does the Science Experiment Work

Why Don’t Oil and Water Mix?

When you shake oil and water together, they may look like they are mixed at first. However, after a short time, the liquids separate into two layers. The oil rises to the top because oil is less dense than water.

Density describes how much matter is packed into a certain amount of space. A liquid with a lower density will float on a liquid with a higher density. Since oil is less dense than water, the oil floats on top.

But what happens when we add dish soap?

Dish soap helps the oil and water stay mixed together. Soap has properties that allow it to interact with both oil and water. The soap helps break the oil into tiny droplets and keeps those droplets spread throughout the water instead of allowing them to quickly join back together.

This is why the mixture looks different when dish soap is added. Instead of the oil quickly separating into a layer on top, the soap helps keep tiny drops of oil mixed throughout the water.

This same property of soap helps us wash greasy dishes. The soap helps lift oil and grease away from the dishes so they can be rinsed away with water.

I hope you enjoyed the experiment. Here are some printable instructions:

Mixing Oil & Water Science Experiment

Print

Materials

• Glass Jar with a lid (a pint canning jar works great)
• 1 cup Water
• Food Coloring
• 1 cup Oil (we used vegetable oil)
• 2 teaspoons Dish Soap

Instructions

1. Start by filling the jar with 1 cup of water.
2. Add a few drops of food coloring to the water and stir until combined.
3. Pour 1 cup of Oil into the jar.
4. Securely tighten the lid on the jar and shake it for 15-20 seconds.
5. Set the jar down and watch the liquid for a minute or two. Observe what happens to the Oil and the Water.
6. Next, take the lid off the jar and squirt in 1-2 teaspoons of dish soap.
7. Tighten the lid back on the jar and shake again for another 15-20 seconds.
8. Set the jar down and watch the liquid for a minute or two. Observe what happens to the Oil and the Water now that the dish soap has been added to the mix.