Chemical Changes: Combustion

Combustion

What is combustion? It is the burning of a complex sequence of chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames. In a complete combustion reaction, a compound reacts with an oxidizing element, such as oxygen or fluorine, and the products are compounds of each element in the fuel with the oxidizing element.

Rapid combustion is a form of combustion in which large amounts of heat and light energy are released, which often results in a fire. This is used in a form of machinery such as internal combustion engines. Sometimes, a large volume of gas is liberated in combustion besides the production of heat and light. The sudden evolution of large quantities of gas creates excessive pressure that produces a loud noise(explosion). Combustion need not involve oxygen. Hydrogen burns in chlorine to form hydrogen chloride with the liberation of heat and light characteristic of combustion.

In complete combustion, the reactant will burn in oxygen, producing a limited number of products. When a hydrocarbon burns in oxygen, the reaction will only yield carbon dioxide and water. When a hydrocarbon or any fuel burns in air, the combustion products will also include nitrogen. When elements such as carbon, nitrogen, sulfur, and iron are burned, they will yield the most common oxides. Carbon will yield carbon dioxide, nitrogen will yield nitrogen dioxide ,sulfur will yield sulfur dioxide and iron will yield iron oxide. However, a complete combustion is almost impossible to form. In reality, a wide variety of major and minor species will be present. For example, the combustion of methane in air will yield, in addition to the major products of carbon dioxide and water, the minor side reaction products carbon monoxide and nitrogen oxides.

Incomplete combustion occurs when there isn't enough oxygen to allow the fuel to react completely with the oxygen to produce carbon dioxide and water, also when the combustion is quenched by a heat sink such as a solid surface or flame trap. When a hydrocarbon burns in air, the reaction will yield carbon dioxide, water, carbon monoxide, pure carbon (usually in the form of soot or ash) and various other compounds.

Combustion is used in everyday's life. Whether is it cooking, running of machines, running factories, the use of combustion is everywhere.