A Simple Experiment to Verify that the Flame of a Candle, covered with a Glass, Goes out before Consuming all the Available Oxygen

Abstract

It is well known that if a lit candle is covered with a glass, the flame quickly weakens and, after a few sec- onds goes out. Since this occurs by limiting the amount of air available for combustion, most people who observe this experiment conclude that the candle goes out due to the depletion of the oxygen trapped in the glass. Research conducted by numerous authors has revealed that this idea is deeply ingrained in students at various educational levels, and even among postgraduates and science teachers. This article presents a simple and reliable method that effectively demonstrates that combustion in a closed space always ceases before all the available oxygen is consumed.