We were having “one of those days” yesterday. Summer break is almost over, and both kids were restless and cranky – stuck inside the house with another afternoon of thunderstorms. My kids are either the best of friends, or best explained like oil and water. When all else fails to stop my kids’ bickering, there is something about the magic of science experiments to force them to get along (at least temporarily!).

Which leads me to our science experiment yesterday. A very simple and fun experiment testing the effect of mixing oil and water using baby oil, water, and food coloring.

The Hypothesis

I began our experiment by filling two vases about halfway up with baby oil (any oil would work, but I used baby oil because it is colorless). Then, I used food coloring to color water in 6 small cups. I added pipettes to each cup. Next, I asked my kids to predict, or hypothesize, what would happen if they added drops of colored water to the oil.

My daughter, age 9, thought the oil and water would fizz. (In her defense, most of my experiments do include fizzing or bubbling of some sort!)

My son, age 7, thought the oil would change colors.

The Experiment

Then, it was time to test their predictions by adding a few drops of colored water to their oil, and observe what happens. After squirting some colored water into the oil, they both realized they had seen something like this before, and exclaimed, “Oh, like a lava lamp!”.

I asked many questions during our experiment, including – why is the water falling through the oil to the bottom of the vase? What is happening to all the colors at the bottom of the vase?

Here is our experiment in action:

The Results

We learned a few things about water and oil – they don’t mix! Water is “heavier” (more dense) than oil, and sinks to the bottom of the container. While the colored water makes its way through the oil, it forms into droplets, until it can sink to the bottom of the container and become a separate layer. (This is because water is polar, meaning it is positively charged at one end and negatively charged at the other. Oil is nonpolar. So, when oil and water are mixed together, water sticks to itself rather than mingling with oil.) Also, when the different colored water droplets reach the bottom of the container, they open and the colored water mixes together.

After the experiment, and the vases were completely filled with oil and colored water, the kids continued to play with the cups of colored water – mixing colors and squirting with the pipettes for at least 45 more minutes. YAY!

So, even though the afternoon began with attitudes like oil and water, it ended with much-improved attitudes mixing and creating new colors.


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