What is the composition of a flame in combustion reactions?

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SUMMARY

The discussion centers on the composition of flames during combustion reactions, specifically the differences between complete and incomplete combustion of alkanes. Yellow flames are primarily composed of superheated carbon soot, while blue flames consist of superheated plasma containing reaction products such as nitrogen and carbon dioxide. The combustion process begins with the decomposition of the fuel into gases, which may either combine with oxygen or produce carbon-rich soot. A practical method to collect carbon soot involves placing a metal object in the yellow part of the flame.

PREREQUISITES
  • Understanding of combustion reactions, particularly alkanes
  • Knowledge of complete vs. incomplete combustion
  • Familiarity with the chemical composition of air (80% nitrogen)
  • Basic principles of thermal decomposition
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Chemistry students, educators, and professionals interested in combustion processes, environmental science, and the chemical properties of flames.

Wellsi
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duh- a bad question i know...

Ok i was in chemistry the other day and we were talking about combustion of alkanes in both complete and non complete reactions... i know that combustion is the oxidation of something... but what exactly IS the flame made when something burns? what is it made of?
 
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Usually the yellow flame is composed of superheated carbon soot. Blue flames are superheated plasma of the reaction products, usually nitrogen and carbon dioxide if it is burning in air. Air is 80% nitrogen which doesn't usually enter into the reaction process but can react with oxygen just outside the blue zone of the flame to produce some brownish oxides of nitrogen we see as smog.

The complete flame starts at the surface of the substance to be combusted. Heat decomposes the stuff into a gas(s) which may combine with oxygen to produce a variety of oxygenates or may thermally decompose to carbon-rich soot. The flame that you see is the brief, fleeting existence of this decomposition just before it combines with oxygen to complely combust.

Want to trap some of that carbon soot? Just place a piece of metal briefly into the yellow part of the flame. Voila! You have trapped the soot on the cool surface which should now appear black.
 
ok thank you... i wasnt quite sure. I know how bad a question it was sorry :P
 

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