Combustion, Phlogiston and Oxygen: An Elemental Discovery
Observe the relationship between combustion and oxygen content in the surrounding air in a closed system and relating this experience to the discovery of the element, oxygen.
PASPORT Oxygen Gas Sensor (PS-2126)
Lab Summary
Students will use the Oxygen Gas sensor to observe the relationship between combustion and oxygen content in the surrounding air in a closed system. Students will relate this experience to the discovery of the element, oxygen.
The discovery of oxygen, one of the most important elements to human survival, occurred mostly by accident. In 1770, prior to understanding the true nature of combustion, G.E. Stahl, a German physician, put forth the theory of phlogiston. The word "phlogiston" was derived from the Greek word meaning "to set on fire." Stahl believed that all objects contained a substance dubbed phlogiston, which, when exposed to inflammatory objects, would be released into the air. The release of this substance, if rapid enough, would be viewed as flames. However, even the rust on metal was considered evidence of the release of phlogiston, albeit in a slower manner.
Later experiments by Scottish chemist Daniel Rutherford further defined the properties of phlogiston. For instance, Rutherford found that using varying sizes of containers determined how long a candle would burn. Rutherford posited that a given quantity of air had a limited capacity for phlogiston, and that once this capacity was exceeded, the flame would extinguish, i.e. the remaining phlogiston stayed in the candle.
In 1774, Joseph Priestly, another phlogiston philosopher, explored the properties of heated mercury in a closed container. Mercury rusts at high temperatures, and Priestly attributed this behavior to a loss of phlogiston as well. It was the intervention of Antoine Lavoisier that would establish the true nature of combustion. Lavoisier ascertained that some element of air was being consumed in combustion, yet others were not. He identified this element as "oxygen". The remaining air would eventually be labeled "nitrogen." Lavoisier's perspective allowed for combustion to be viewed in appropriate terms, an exothermic chemical reaction limited by the availability of oxygen.
Hypothesize: How will the size of the jar affect the burning time of the candle? How does oxygen feed the flame? Will the flame extinguish before or after the oxygen is completely used up?
Published: October 2003
Downloads
- Combustion, Phlogiston and Oxygen - PASPORT (21 KB, .zip)
Includes experiment setup, procedures and Datastudio file
Here's What You Need
U.S. Educator prices shown.
Probeware (PASPORT Systems)
Xplorer GLX (PS-2002) - $329
The Xplorer GLX is a data collection, graphing, and analysis tool designed for science students and educators.
PASPORT Oxygen Gas Sensor (PS-2126) - $195
The Oxygen Gas Sensor accurately measures oxygen concentration in the atmosphere or in enclosed spaces.
Other Materials
- Modeling clay
- Several pieces of cardboard
- Several jars or beakers of varying size
- Several tea-light sized candles
- Lighter or matches