In CHE321 (Inorganic Laboratory) SQ2016, our students performed a variety of experiments related to inorganic chemistry. One of the most visually stunning was the synthesis of ferrofluids. Ferrofluids are liquids that respond to magnetic fields. Students synthesized them from Fe(II) and Fe(III) chloride salts and ammonia, which results in magnetite nanoparticles. These nanoparticles were then suspended in a solution to make the ferrofluid. In the absence of a magnetic field, ferrofluid is a black viscous liquid, but it responds strongly to magnetic fields.
Below are two pictures from students, used with permission (top image: Pheobus Sun Cao – ferrofluid in a vial, bottom image: Marcellus Johnson – ferrofluid in a weigh boat). In both photos, you can see how the ferrofluid “spikes” in the presence of a magnet.