What is "combustion"?

Apr 1, 2017

Combustion is the reaction of an oxidant (typically oxygen gas) with a combustible reactant. For organic compounds, combustion results in the formation of carbon dioxide and water (and energy).

Explanation:

And typically, for organic hydrocarbons, ${C}_{n} {H}_{m}$, the products of combustion are carbon dioxide, and water. The energy released when $C = O$, and $H - O$ bonds are formed can be utilized to do work.

For an alkane, ${C}_{n} {H}_{2 n + 2}$ we may represent the combustion reaction as:

${C}_{n} {H}_{2 n + 2} \left(l\right) + \frac{3 n + 1}{2} {O}_{2} \left(g\right) \rightarrow n C {O}_{2} \left(g\right) + \left(n + 1\right) {H}_{2} O \left(l\right) + \Delta$

Let us try this formula out for hexane combustion:

${C}_{6} {H}_{14} + \frac{19}{2} {O}_{2} \rightarrow 6 C {O}_{2} + 7 {H}_{2} O + \Delta$

And for methane combustion:

$C {H}_{4} + 2 {O}_{2} \rightarrow C {O}_{2} + 2 {H}_{2} O + \Delta$

The heat output can also be stoichiometrically assessed.

And these reactions, as energy sources, allow humanity to live beyond thirty. Given that hydrocarbon reserves are finite, and we have reached the era of peak oil, we should all have a fundamental understanding of the process of combustion.

Here, we have represented complete combustion, but sometimes, especially in the internal combustion and diesel engines, combustion is incomplete, and $C O$ and particulate $C$ results as products. Can you represent this in an equation?