5.1 The Combustion of Hydrocarbons

Background Organic Compound: a molecular compound containing one or more carbon-carbon bonds

Manny fuels contain impurtities such as sulfur compounds and heavy metals. These impurities cause air pollution The burning of hydrocarbons is a large contributing factor to the release of carbon dioxide into the atmosphere. Carbon dioxide is one green house gas that contributes to the theory of global warming.

Combustion Reaction Requires the presence of oxygen for complete combustion The reactants are any material and oxygen The general equation for a complete combustion reaction of a hydrocarbon is: Hydrocarbon + oxygen → carbon dioxide + water C3H8 (g) + O2 (g) → CO2 (g) + H2O (g) 2C3H8 (g) + 10O2 (g) → 6CO2 (g) + 8H2O (g)

The general equation for a combustion reaction of an element is: compound + oxygen → oxides of the compound S8 (g) + 8O2 (g) → 8SO2 (g)

Incomplete Combustion Combustion of a hydrocarbon occurs when the supply of oxygen is limited. It is said to be “fuel rich” Flames from incomplete combustion are often yellow, sooty and considerably cooler than flames from complete combustion. They produce a wider range of products and are generally represented by more than one chemical equation

Incomplete combustion of Heptane C7H16 (g) + 7O2 (g) → 3C(s) + 2CO (g)+ 2CO2 (g)+ 8H2O (g) + energy C7H16 (g) + 11O2 (g) → 14CO (g)+ 2CO2 (g)+ 8H2O (g) + energy

Using page 194-195 address the concerns related to incomplete combustion