What is the difference between a complete and incomplete combustion reaction?

Question

Wyatt Adkins · Accepted Answer

Typically complete and incomplete combustion relates to the combustion of hydrocarbons. Here, complete combustion indicates that carbon dioxide is the sole oxidation product; incomplete combustion means otherwise.

Let's use octane as an example: #C_8H_18(g) + 25/2O_2(g) rarr 8CO_2(g) + 9H_2O(g)# Is the above equation balanced? Don't trust my arithmetic! Here, all the hydrocarbon reactant ends up as carbon dioxide product; the carbon in the hydrocarbon is completely combusted to #CO_2#. Under the conditions of a ICE or diesel fuel engine, combustion would be incomplete, and some products of incomplete combustion, #CO#, or particulate #C#, would result. I can represent this by the following reaction: #C_8H_18(g) + 11O_2(g)rarr 6CO_2(g) + CO(g) + C(s) + 9H_2O(g)# Once more, is this balanced? If not, why not? This is just a representation; an analysis of the products would be necessary to determine the efficacy of combustion.

Wyatt Atkins · Answer

undefined Complete combustion produces only carbon dioxide and water, while incomplete combustion results in additional byproducts like carbon monoxide or unburned carbon.