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Combustion reactions (view source)
Revision as of 17:34, September 18, 2007
, 17:34, September 18, 2007added general reactions
'''Combustion reactions''' (informally known as simply ''burning'') are chemical reactions in which a substance is reacted [[exothermic]]ally with molecular [[oxygen]] (O<sub>2</sub>) at a high temperature. Combustion reactions can either be ''complete'' or ''incomplete''.<ref name="ref1">What is combustion? [http://www.habmigern2003.info/1_combustion.html]</ref>
'''Combustion reactions''' (informally known as simply ''burning'') are chemical reactions in which a substance is reacted [[exothermic]]ally with molecular [[oxygen]] (O<sub>2</sub>) at a high temperature. Combustion reactions can either be ''complete'' or ''incomplete''.<ref name="ref1">What is combustion? [http://www.habmigern2003.info/1_combustion.html]</ref>
In ideal circumstances, all reactions would be complete; or in other words, oxygen would fully [[oxidize]] the other [[reactant]]s. For example, a combustion reaction involving a [[hydrocarbon]] (any molecule consisting only of carbon and hydrogen) would result in only carbon dioxide (CO<sub>2</sub>) and and water (H<sub>2</sub>O) as products (possibly with excess oxygen).
In ideal circumstances, all reactions would be complete; or in other words, oxygen would fully [[oxidize]] the other [[reactant]]s. For example, a combustion reaction involving a [[hydrocarbon]] (any molecule consisting only of carbon and hydrogen) would result in only carbon dioxide (CO<sub>2</sub>) and and water (H<sub>2</sub>O) as products (possibly with excess oxygen). The general form of complete saturated hydrocarbon combustion is as follows:
In the real world, however, combustion reactions rarely go to completion. This is due to imperfect conditions, such as insufficient oxygen or low ignition temperature.<ref name="ref1" /> Incomplete combustion results in additional products which are not fully oxidized. For example, an incomplete combustion reaction involving a hydrocarbon would include [[carbon monoxide]] (CO) as a product, along with carbon dioxide and water.
:<math>C_nH_{2n+2} + (\frac{3}{2}n + \frac{1}{2})O_2 \rightarrow nCO_2 + (n+1)H_2O</math>
In the real world, however, combustion reactions rarely go to completion. This is due to imperfect conditions, such as insufficient oxygen or low ignition temperature.<ref name="ref1" /> Incomplete combustion results in additional products which are not fully oxidized. For example, an incomplete combustion reaction involving a hydrocarbon would include [[carbon monoxide]] (CO) as a product, along with hydrogen (H<sub>2</sub>), carbon dioxide and water.
:<math>C_nH_{2n+2} + mO_2 \rightarrow XnCO_2 + (1-X)nCO + Y(n+1)H_2O + (Y-1)H_2</math>, where
*X is the fraction of carbon completely combusted
*Y is the fraction of hydrogen completely combusted
*m is the molar ratio of oxygen fed to the system, equal to <math>n(\frac{3}{2}X + \frac{1}{2}Y + \frac{1}{2})</math>
==References==
==References==