Crude oil and hydrocarbonsPetroleum, also known as crude oil, is formed from the fossilized remains of marine plants and animals that settled on the seabed ago is millions of years old. Petroleum is made up of a complex mixture of hydrocarbon molecules including paraffins, aromatics, naphenes/cycloalkanes, alkenes and alkynes. Hydrocarbons are molecules that contain hydrogen and carbon atoms that form various structures ranging from straight chains to branched chains and rings. Low molecular weight hydrocarbons, such as propane (C3H8), are in gaseous form. Octane and kerosene are both liquids and have medium molecular weights, while larger hydrocarbons are solids such as tar and bitumen. Fractional Distillation Oil drilling takes place both on land and offshore and is then transported to an oil refinery. Fractional distillation is the process in which hydrocarbon chains of different lengths are separated by their boiling points, which depend on length. These strings of different lengths are called fractions. Shorter carbon chains evaporate more easily than longer chains. In order to separate the chains of different lengths in the crude oil, the mixture is heated to very high temperatures in a distillation tower. The distillation tower becomes progressively colder from the base to the top, and as all the hydrocarbons begin in the gas stage, they rise. As the vapors rise, fractional condensation occurs in different sections of the tower (Roger, 2010). Some products derived from crude oil include: petroleum gas, naphtha, petroleum, kerosene, lubricating oil, fuel oil and residues such as asphalt and tar. Although all fractions of crude oil have uses, the greatest demand requires that more than 50% of the crude oil be converted...... middle of paper ......e, (date unknown), Refining of petroleum by distillation, accessed August 18, 2010, http://www.elmhurst.edu/~chm/vchembook/513refining.htmlKovarik W. & Hermes EM (date unknown), Chemistry of Petroleum Cracking, accessed August 19, 2010, http ://www.chemcases. com/fuels/fuels-b.htmRoger (2010), Fractional Distillation of Crude Oil, accessed August 20, 2010, http://www.green-planet-solar-energy.com/fractional-distillation-of-crude-oil . htmlFrance, C. (2008), Petroleum products, accessed August 21, 2010, http://www.gcsescience.com/o33.htmScifun. (date unknown) Chemical of the Week – Polymers, accessed August 18, 2010, http://scifun.chem.wisc.edu/chemweek/polymers/polymers.htmlAmerican Chemistry Council (2010), Life cycle of a plastic product, date accessed August 18, 2010, http://www.americanchemistry.com/s_plastics/doc.asp?CID=1571&DID=5972