Isn’t this pretty? This was one of our experiments as we finished up our chemistry unit!
One of the chapters in our chemistry book (Real Science 4 Kids-pre-level 1) talked about mixtures. It talked first about how how some mixtures dissolve (like salt in water). Then it went on to talk about soap and soap molecules. We read how soap makes things like butter and grease “dissolve” in water. Detergent is attracted to both oil and water helping them join together.
We did a little experiment to show how soap helps get your dishes clean. We took a couple of baby food jars and put oil and colored water into each. Then to one of the jars we added dish detergent. We all watched as the detergent took its time and then slowly sank down through the layer of oil. We shook both jars vigorously and then set them to the side for 20 or 30 minutes.
When we came back, we could see that the jar without detergent had separated back into two layers — oil and water. In the other jar, the oil and water still seemed to be mixed together. The older kids learned that this is called an emulsion.
While we were waiting for the experiment above to finish we went on to another mesmerizing activity. We’ve done this before and it never fails to captivate us! All you need is milk in a bowl, food dye, detergent and a Q-tip. You place a few drops of dye into the milk, dip the Q-tip into detergent and then very gently place the Q-tip into the water. The colors start racing around. The kids then dipped their Q-tip into the detergent again and gently placed it back in the milk in a different spot. The colors start moving and swirling about. It’s really pretty to watch!
The action in this experiment is a bit complex. Our chemistry book showed how soap molecules have different properties. Our book explained it as one end being “oil-like” and the other, “water-like.” Oil dissolves in the oil-like ends of the soap and becomes surrounded by the water molecules. This experiment shows the movement of molecules as the fat molecules are interacting with the soap detergent molecules.
Steve Spangler explains this milk experiment this way, “The molecules of fat bend, roll, twist, and contort in all directions as the soap molecules race around to join up with the fat molecules. During all of this fat molecule gymnastics, the food coloring molecules are bumped and shoved everywhere, providing an easy way to observe all the invisible activity. As the soap becomes evenly mixed with the milk, the action slows down and eventually stops.”
Other sources explain that other factors are at work here such as breaking the surface tension of the liquid, etc. If your child is older you could discuss those other factors as well.
At any rate, it’s a colorful fun experiment to do with anyone from pre-K on up. Who doesn’t like watching colors swirl and whirl?!
I made a copy of this experiment and the explanation of how it works that you can print off:
Our final experiment didn’t really connect with our chemistry chapter, but was another fun, color experiment to do with the kids. We took skittles and dissolved them in water. (You can also use M&Ms) I had the kids guess whether the colors would mix or stay separate. The older kids, of course, remembered doing this a few years ago, but ED didn’t. We talked about how scientists “make predictions” and then perform experiments to see if their prediction was accurate.
Skittles (or M&Ms) have an edible dye that doesn’t dissolve in water. There was equal pressure from all sides as the dye moved towards one another so the colors stopped moving forward. I explained it to the kids as if we had our palms out and were both leaning a little bit toward each other.
Do you want to do other fun experiments with candy? Be sure to visit this great website, Candy Experiments written by Loralee, a mom of three. I visited the booth they had set up at the USA science and engineering festival last year and the kids loved some of the experiments they had set up!
Science Experiment Pack: Back about five months ago I made a packet of some of our most beloved science experiments. If you’re keen to do science experiments with your kids, here are some of the things that my kids and I have enjoyed a lot:
Download your free Science Experiment Packet
You can find more of our science experiments by clicking on the categories button in the left sidebar. Or, you can find activities related to different science topics we’ve covered such as
- the human body
- earth science
- rocks and minerals
- animal habitats/biomes
Have fun experimenting with your young scientist!!
I’ll be taking some time off with my family and will return next Wednesday with more of our homeschool adventures.
Have a safe and Happy Thanksgiving holiday!
Other fun Chemistry Experiments:
- Chemistry Experiments for Kids (Grade 2) – Matter is Neither Created Nor Destroyed — Acids and Bases – Free Chemistry Experiment Printable Packet
- Chemistry Experiments for Kids (Grade 2) – Mixtures, Chromatography, DNA Kit – Free Chemistry Experiment Printable Packet
- We all enjoyed the IMAX film, Molecules to the Max which is out on DVD (see more about it at this post)