Changes of CO[subscript 2] Concentration and Heat Illustrate Why the Flame Is Extinguished in the Candle-and-Cylinder Experiment

Autor/inn/en	Que, Ronghui; Sha, Sha; Shen, Liqun; Xiong, Yanlin
Titel	Changes of CO[subscript 2] Concentration and Heat Illustrate Why the Flame Is Extinguished in the Candle-and-Cylinder Experiment
Quelle	In: Journal of Chemical Education, 97 (2020) 4, S.1195-1197 (3 Seiten)Infoseite zur Zeitschrift PDF als Volltext Verfügbarkeit
Zusatzinformation	ORCID (Que, Ronghui)
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	0021-9584
Schlagwörter	Chemistry; Science Instruction; Comparative Analysis; Laboratory Experiments; Teaching Methods; Misconceptions; Heat; Laboratory Equipment; Elementary School Students; Middle School Students + Suchen Sie Ihr Suchwort? Chemie; Teaching of science; Science education; Natural sciences Lessons; Naturwissenschaftlicher Unterricht; Laboratory work; Laborarbeit; Teaching method; Lehrmethode; Unterrichtsmethode; Missverständnis; Hitze; Laborausstattung; Middle school; Middle schools; Student; Students; Mittelschule; Mittelstufenschule; Schüler; Schülerin
Abstract	The extinguishment of the candle flame in the well-known candle-and-cylinder experiment has been erroneously viewed as caused by the complete consumption of oxygen, for many reasons. To address this misconception scientifically, a series of experiments are carried out to illustrate the phenomenon from a new point of view. Limewater [Ca(OH)[subscript 2]] placed at different heights in a container was used to qualitatively describe the distribution of CO[subscript 2] in an enclosed cylinder with one or two burning candles. Temperature sensors, CO[subscript 2] sensors, and oxygen (O[subscript 2]) sensors were employed to visually and quantitatively compare the content of CO[subscript 2] at different heights within the container. The resulting temperature curves show that the heat from combustion rose first and then descended soon afterward. Chemical and sensor detection of CO[subscript 2] in the highest two quadrants of the container indicated that the hot CO[subscript 2] gas rose initially and accumulated there in the highest part of the container. Then, the hot CO[subscript 2] gas descended gradually and created a CO[subscript 2] atmosphere surrounding the flame. As a result, the flame was extinguished by the buildup of CO[subscript 2] and depletion of oxygen in the gas in the vicinity of the flame. The change of oxygen concentration showed that there was a mixing process between the remaining air and the hot CO[subscript 2]. These results indicate that the extinguishment of the flame does not mean that the oxygen in the container was completely consumed. Knowing this helps students understand that the density of CO[subscript 2] depends on its temperature. (As Provided).
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Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2024/1/01