combusting

Combusting refers to undergoing combustion, a high-temperature exothermic chemical reaction between a fuel and an oxidizer that releases heat and often light. It is a form of rapid oxidation, typically characterized by the presence of a flame and sustained heat.

For combustion to occur, three elements are usually required: a combustible substance (fuel), an oxidizer (commonly atmospheric oxygen), and an ignition source to reach the activation energy. Removing any element—fuel, oxidizer, or heat—prevents combustion. Some processes use oxidizers other than oxygen, such as chlorine or nitrates, in specialized applications.

The process is driven by chemical reactions at the molecular level. In hydrocarbon combustion, fuel molecules react with oxygen to form products such as carbon dioxide and water, releasing energy. Incomplete combustion can produce carbon monoxide, soot, and other unburned hydrocarbons. The presence of flames, heat transfer, and mixing influences whether the combustion is complete or incomplete.

Combustion occurs in various regimes. Rapid combustion produces flames (deflagration) when heat transfer is slower than the chemical reaction, and detonation when shock waves drive much faster reactions. Slow oxidation can occur without flames, as in rusting.

Common examples include burning of fuels in engines, stoves, or wood fires. Combustion is a major energy source but also a principal source of emissions, requiring control to minimize pollutants and enhance safety.