Ben Cromwell investigates flame retardants at the University of Rhode Island. His group normally uses cotton balls like the ones shown for small-scale tests of the fire-suppressing power of new substances and methods. But in this demonstration, they wanted to capture the colors of copper bromide (left) and cesium carbonate flames. So he doped the cotton balls with the metal salts, added methanol, and set them alight. Different metals produce differently colored flames, an effect also employed in fireworks.
Safety note: Cromwell and his colleagues are trained in fire safety and conducted this demonstration in an appropriate apparatus. To do a similar demonstration at home or in a classroom, C&EN recommends a different procedure, detailed at goo.gl/scPZ1m.
Submitted by Ben B. Cromwell/University of Rhode Island
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