Kids totally know that oil and water don’t mix. But giving an explanation as to why, is where the chemistry comes in. I like this Like Dissolves Like lab activity because you can dress it up or down as you like. Plus it’s great for a confirmation inquiry activity. (That’s where you have students confirm what they already know or suspect to be true.) If you’re looking for a lab rubric to help your students communicate their findings, sign up here and get a copy sent to your inbox.
Like Dissolves Like Lab Activity
I usually set this up as stations, for ease of setup and cleanup. I give my students test tubes, water and a bunch of different substances. They add some water to the test tube and then add a few drops of each substance. This helps them to determine if the substances is polar or nonpolar. There’s two pieces of information used for this. One is the result of the Like Dissolves Like test, and the second is evaluating the Lewis Structure.
The substances in this hands on activity for teaching likes dissolves like are usually found in a kitchen. I’ve done a few different versions of this lab and different substances each time. Here’s a list of things I’ve used:
- food coloring
- rubbing alcohol
- baby oil
- mineral oil
- corn oil
- olive oil
- vinegar
- milk
- orange juice
- hydrochloric acid
- liquid soap
- vanilla extract
- soy sauce
In all honesty, it doesn’t matter so much what chemicals you choose to complete the lab. Especially if you aren’t so much focused on the Lewis Structure. As long as you have a decent mix of polar and nonpolar substances, you can really get away with choosing whatever substances you have available to you. I started out teaching chemistry in a retired art classroom, so my collection of lab activities are usually low maintenance.
Knowing that water is polar, it’s easy for students to determine what other chemicals in the mix are also polar. You can even have the students mix together two or three (non-reacting) nonpolar substances to really test the hypothesis.
Mind Blowing Trick
Now here’s a doozy. I actually made a home-made always dry sand. I put the sand in a disposable aluminum tray because the chemicals are really stinky. Then I put some decorative sand in the tray and sprayed it with this waterproofing camping spray. I do a little bit of stir, spray, stir spray until I feel like I’ve sprayed all the sand. You can see the color deepen from the spray, so it’s decently easy to tell. Around 24 hours later, I will check on the sand and test it in some water. The best part about this strategy is that as the sand loses it’s waterproof qualities, you can spray it some more. It took me around 10 uses to need to redo the sand. Read detailed instructions on how to make the sand here.
Sand should be able to mix with water and become wet, but when it doesn’t the students now have a question to answer. Why doesn’t the sand mix well with water like it should? How can this sand come out dry? You could get really crazy and give them two samples of sand – one that is waterproofed, and the other in its natural state. This always leads to awesome class discussions. I’ll tell you, this hands on like dissolves like activity is one my students rarely forget.
