Reactions - Combustion

Simply, combustion is the burning of matter. Different types of matter burn under different conditions.


Explore the discoverer's biography, including general facts about his life and anecdotes regarding how he made this particular discovery. Also see other significant scientific discoveries built largely on this concept and other real-world applications in history that may not still be relevant.


Formulated in the 1600s, the phlogiston theory views combustion as the escape of some “inflammable principle” when the “combustible bodies” react with air. In 1650, the German physicist Otto von Guericke demonstrated that a candle would not burn in the absence of air. In 1665, the English scientist Robert Hooke learned that a nitre (a mineral form of KNO3) and sulfur mix can burn without air. In 1772, French chemist Antoine-Laurent Lavoisier discovered that the final product of a combustion reaction was greater than the reactants, and concluded that the excess weight was due to the reactants combining with the air. Sir Humphry Davy, an English chemist, discovered catalytic combustion in the late 1810s, where the reaction produces only heat and no flame. Based on the concept of heat as the movement of particles that was proposed by chemist Sir Benjamin Thompson in 1798 with thermodynamics, energy was included as a product of combustion reactions beginning in the 19th century.


Concept Definition

Study the primary definition of this concept, broken into general, basic, and advanced English definitions. Also see the mathematical definition and any requisite background information, such as conditions or previous definitions.

General Science

Combustion is a chemical process during which a fuel, oxygen, and heat react rapidly to produce chemical species such as CO2 and H2O in addition to heat and, typically, light. Combustion is sometimes referred to as a burning process. The reaction rate of a combustion reaction is usually fast.


Combustion reactions usually require initiations in forms of heat, light and spark. The minimum temperature required to initiate a combustion reaction is dependent on the pressure of the reaction system.

Oxygen, carbon monoxide, and hydrocarbons are the most commonly seen reactants and carbon dioxide and water are often formed as products of basic combustion reactions. Some examples to illustrate that include:

1. $\text{H}_2_{(g)} + \text{O}_2_{(g)} \to \text{H}_2\text{O}_{(g)}$

2. $\text{CO}_{(g)} + \text{O)_2_{(g)} \to \text{CO}_2_{(g)}$

3. $\text{CH}_4_{(g)} + \text{2O}_2_{(g)} \to \text{CO}_2_{(g)} + \text{2H}_2\text{O}_{(g)}$

Nitrogen as a major component of air generally does not participate in combustion reactions. The insert of nitrogen, or other types of gas such as noble gas that are relatively stable and inactive, will result in dilution of the reaction mixture and thus the combustion reaction will become slower. This helps us to understand why ethane burns slower in air than in pure oxygen.

$\text{2C}_2\text{H}_6_{(g)} + \text{7O}_2_{(g)} + \text{nN}_2_{(g)} \to \text{4CO}_2_{(g)} + \text{6H}_2\text{O}_{(g)} + \text{nN}_2_{(g)}$

However, the reaction between nitrogen and oxygen can occur at temperatures above 2,800 °F (1,540 °C). Common nitrogen oxides include nitric oxide (NO) and nitrous oxide (NO­2).

1. $\text{N}_2_{(g)} + \text{O}_2_{(g)} \to \text{2NO}_{(g)}$
2. $\text{N}_2_{(g)} + \text{2O}_2_{(g)} \to \text{2NO}_2_{(g)}$

Incomplete combustion reactions occur in systems that lack enough oxygen to completely react with the hydrocarbon or the percent mass of carbon in the hydrocarbon compound is too large (such as benzene, C6H6); in these cases, carbon monoxide might appear as one of the products instead of or in addition to carbon dioxide.

1. $\text{2CH}_4_{(g)} + \text{3O}_2_{(g)} \to \text{2CO}  \text{4H}_2\text{O}_{(g)}$

2. $\text{C}_6\text{H}_6_{(g)} + \text{O}_2_{(g)} \to \text{CO}_{(g)} + \text{CO}_2_{(g)} + \text{H}_2\text{O}_{(g)}$

             (Note: the second equation is not balanced)


Combustion is defined as the burning of a fuel and an oxidant to produce heat and/or work.

Most combustion reactions require oxygen to be present as well as fuel and heat.


Real World Application

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The burning of coal, a type of fossil fuel, is one of the most common real world applications of combustion to produce heat and energy. Combustion of coal, petroleum, hydrogen, biomass, etc. generates the largest amount of electricity worldwide. In the U.S., energy from coal is the major source (46.5%) of electricity production from June 2008 to June 2009, as shown in the pie graph below:


(Credit: Mike Corradini)

As a common combustion product, CO2 is critical for global warming. Combustion of coal emits by far the greatest amount of CO2 for the same amount of energy comparing to other types of energy sources, as illustrated in the bar graph below:


(Credit: Mike Corradini)

Other sources of energy include nuclear energy, renewable energy such as wind energy and solar energy, and so on, but they have constrains such as safety and cost. Although it might take decades to improve energy production technologies, they should be developed to provide more environmentally friendly and reliable energy sources for the future.



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 Important Vocabulary

Term Context



Browse relevant videos from the Journal of Chemical Education's (JCE) Chemistry Comes Alive! library and other video sources.

Hexane Burn

Hexane Burn with Water

Hexane burns, and water is unable to put it out.


Computer Animations

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Works Cited

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 Works Cited

"Combustion." Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica, 2011. Web. 25 Mar. 2011. <>.

Corradini, Mike. "Energy Use Sources & Prospects in the 21st Century." Interdisciplinary Engineering 11th Lecture. 1800 Engineering Hall, niversity of Wisconsin - Madison, Madison, WI. 28 Feb. 2011. Lecture.

Foster, David E. "Energy and Advanced Automobile Technology for a Carbon Constrained World." Interdisciplinary Engineering 160 20th Lecture. 1800 Engineering Hall, University of Wisconsin - Madison, Madison, WI. 6 Apr. 2011. Lecture.

Zhou, Chenn. "Combustion." Encyclopedia of Earth. 14 July 2010. Web. 18 Feb. 2011. <>.(DefinitionAdvanced)

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