Crude oil is a complex mixture of hydrocarbons formed over millions of years from decomposed organic matter under high pressure and temperature beneath the Earth's surface. Through fractional distillation of crude oil, different hydrocarbon compounds are separated based on their boiling points, producing various useful products from fuels to plastics.
The most common hydrocarbons found in crude oil are alkanes, which are saturated hydrocarbons with single bonds between carbon atoms. When these hydrocarbons undergo combustion, they can experience either complete or incomplete combustion depending on oxygen availability. Complete combustion occurs with sufficient oxygen, producing carbon dioxide and water vapor. However, when oxygen is limited, incomplete combustion produces carbon monoxide, carbon (soot), and water vapor, which can be harmful to the environment and human health. The word equation for combustion of hydrocarbon shows this relationship: hydrocarbon + oxygen → carbon dioxide + water (complete) or hydrocarbon + oxygen → carbon monoxide + carbon + water (incomplete).
Another important aspect of organic chemistry is the formation of polymers through addition polymerisation. This process involves alkenes, which are unsaturated hydrocarbons containing double bonds, joining together under specific conditions to form long chains of molecules. The conditions for addition polymerisation typically include high pressure, moderate temperature, and sometimes a catalyst. This process is crucial in producing common plastics like polyethylene and polypropylene. Understanding the reactions of alkenes and their transformation into polymers is fundamental to modern materials science and industrial chemistry. The distinction between alkanes and alkenes is particularly important in GCSE Chemistry, as their different structures lead to distinct chemical properties and reactions.
