Oil Facts

  • Oils are liquids that do not dissolve in water and burn easily.
  • Oils are usually made from long chains of carbon and hydrogen atoms.
  • There are three main kinds of oil: essential, fixed and mineral oils.
  • Essential oils are thin, perfumed oils from plants. They are used in flavoring and aromatherapy.
  • Fixed oils are made by plants and animals from fatty acids. They include fish oils and nut and seed oils.
  • Mineral oils come from petroleum formed underground over millions of years from the remains of micro-organisms.
  • Petroleum, or crude oil, is made mainly of hydrocarbons. These are compounds made only of hydrogen and carbon, such as methane (see oil compounds).
  • Hydrocarbons in petroleum are mixed with oxygen, sulphur, nitrogen and other elements.
  • Petroleum is separated by distillation into various substances such as aviation fuel, petrol or gasoline and paraffin. As oil is heated in a distillation column, a mixture of gases evaporates. Each gas cools and condenses at different heights to a liquid, or fraction, which is then drawn off.
  • Hydrocarbons are compounds made only of carbon and hydrogen atoms. Most oil products are hydrocarbons.
  • The simplest hydrocarbon is methane, the main gas in natural gas (and flatulence from cows!). Methane molecules are one carbon atom and four hydrogen atoms.
  • Alkanes or paraffins are a family of hydrocarbons in which the number of hydrogen atoms is two more than twice the number of carbon atoms.
  • Lighter alkanes are gases such as methane and propane which make good fuels.
  • Candles contain a mixture of alkanes.
  • Alkenes or olefins are a family of hydrocarbons in which there are twice as many hydrogen atoms as carbon atoms.
  • The simplest alkene is ethene, also called ethylene (C2 1-1 4) which is used to make polythene and other plastics such as PVC.
  • Green bananas and tomatoes are often ripened rapidly in ripening rooms filled with ethene.
  • Ethene is the basis of many paint strippers.
  • Ethene can be used to make ethanol, the alcohol in alcoholic drinks.