In this lab, students are presented with nine unknown substances. By performing a series of tests, analyzing chemical structures, and applying their understanding of how intermolecular forces affect the properties of a substance, students will ultimately determine the identity of each unknown.
Students use a micro-scale method to extract caffeine from tea using dichloromethane. At the end of the activity, the students' dochloromethane extractions are pooled; the solvent is distilled after class for re-use.
Melissa Hemling shares her favorite manipulatives along with cheap at-home alternatives to help students visualize VSEPR.
Determination of Lewis Dot structures and visualization of the shapes of molecules using VSEPR theory is an example of an abstract concept that students often find difficult to learn. I have found it useful to have a single worksheet/packet that my students can add to as we cover Lewis dot structures, resonance, VSEPR shapes, polarity, and intermolecular forces.
Some orange peels can cause balloons to pop. The compound in orange peels called limonene is responsible for this effect. Limonene is responsible for the wonderful smell of oranges, and it is a liquid at room temperature.
I was looking for a new demonstration to initiate a discussion about polarity and related properties to use as part of an exam review. I found a video at ChemEd X (this is part of a ChemEd X subscription). It is entitled “Floating Squares – Hexane and Water” (see note below). I have placed both solutions together before, but I had not added the squares. The demonstration fulfilled my needs. I could have used the original video and muted it if I had not had hexane to demonstrate with.
Wow! A very neat experiment, called “Hydroglyphics”, published by Kim, Alvarenga, Aizenberg, and Sleeper in the Journal of Chemical Education allows you to transform a common plastic Petri dish into a unique teaching tool to demonstrate the difference between hydrophobic and hydrophilic surfaces. Check it out in the video.