Chemistry in Pictures: O Chemistree

Andres Tretiakov, a physics technician at St. Paul’s School in London, made this density column chemistree as part of a demonstration for students using a few kitchen staples and a tree-shaped glass bottle. The bottom layer of the column is Karo corn syrup, followed by blue food coloring in water, then olive oil, then acetone with “a pinch of turmeric powder”—each successive layer of liquid lower in density than the one below it. And, as a bonus, each layer is fluorescent under 365 nm light. Curcumin in the turmeric emits a “joyous yellow-green colour.” Olive oil glows blue thanks to polyphenols, vitamins, and chlorophyll derivatives (the exact hue depends on the type of olive oil—Tretiakov used light refined oil). The blue food coloring is made with spirulina, an edible blue-green algae which produces red-fluorescing phycocyanin pigments. Finally, the source of the blue fluorescence in the corn syrup likely comes from a blend of fluorescent polysaccharides.

Credit: Andres Tretiakov

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