@chemicalkim: When you heat a copper penny until it glows red, it reacts with oxygen to form copper oxide. Turning off the light makes the glow more visible. Even when removed from the butane torch, the penny stays red-hot because it is suspended over acetone. The copper oxide reacts with acetone, forming ketene and methane, and regenerating the copper on the penny's surface. This exothermic reaction releases heat, keeping the penny hot and glowing. The process repeats as long as there's acetone vapor, but stops when the acetone is depleted. This demonstration should be conducted in a fume hood due to the toxicity of ketene. #chemistry