Intermolecular Forces

The Density Bottle experiment has inspired many colorful variations over the years.^1-6 I recently came across yet another colorful variation that I’d like to discuss.

by Dean J. Campbell* *Bradley University, Peoria, Illinois

Would you like to take a walk with me through the chemical winter wonderland of snowflakes? Well, we chemists know that the stunning six-sided symmetry of snowflakes (Figure 1) results from repeated arrangement of water molecules into a hexagonal crystal structure (Figure 2).

A variety of interesting coloring books are available on the market that use water as a coloring agent.¹ When water is applied to the pages of these books, colors seem to appear like magic. When the water evaporates, the colors disappear. This allows the pages of these books to be colored over and over again.

The Intermolecular Force Lava Lamp Lab is a beloved activity among our first-year chemistry students. By integrating particulate model scaffolds into the classic Lava Lamp Lab, we aim to make the concept of intermolecular forces more accessible, reducing cognitive load and improving overall comprehension.

In “salting out” demonstrations, a mixture of water and an organic liquid separates into two layers upon addition of an inorganic salt.^1-4 Typically, acetone or various alcohols are used for the organic liquid, while NaCl, Na₂CO₃, or K₂CO₃ are used as the salt.

In Chemical Mystery #19,¹ a yellow liquid is poured into a test tube, and the liquid turns red. When a white sold is added to the red liquid in the test tube, the liquid turns blue.

Molecular kits are a large investment for a chemistry classroom and often they only get used once a year during a VSEPR activity. My students love to play with molecular kits as it reminds them of building with LEGOS.

Time for a new chemical mystery! Watch the video below and see if you can use your chemical knowledge to figure out how this experiment is done.