Intermolecular Forces of Attraction Lab

For years I struggled with teaching IMF's because I didn't have a concrete lab to show the students the macroscopic effect of stronger intermolecular forces. I developed this lab to show this. The preview shows you one of the 4 different macroscopic properties that are analyzed in this lab.

Each property has a small lab that the students can perform to collect data. There is data table for them to complete, as well as analysis questions which allow students to make connections from the macroscopic to the molecular level. For example, students are asked to describe which substances displayed stronger intermolecular forces based on their data. Then, they compare that to the structure of the molecules involved. Based on their knowledge at this point, they should be able to determine the intermolecular forces present (London dispersion, dipole, hydrogen bonding) and determine if their macroscopic observations match the predicted intermolecular forces.

I also introduce this lab by beginning with a ketchup race. I place 5 blobs of different ketchups at the top of a whiteboard. After beginning "Chariots of Fire", I raise the board on an angle and allow the ketchup to begin sliding down the board. I have the students pick their favorite and cheer - first ketchup to the finish line at the bottom wins. We then connect this to the property of viscosity and then begin the lab. This ketchup race is an idea from Jeff Bracken.