Crude oil and its products

• Crude oil is a fossil fuel like coal and natural gas.
• Crude oil contains a mixture of hundreds of carbon compounds.
• Most of the compounds in crude oil are hydrocarbons – compounds containing only hydrogen and carbon.
• The hydrocarbons in crude oil can be separated into fractions by fractional distillation.
• The boiling points and other properties of these fractions differ and as a result they have different uses.
  
• Cracking is used to produce additional qualities of petrol from the heavier fractions of crude oil. During cracking, larger alkane molecules are split into smaller alkanes plus alkenes using a catalyst at high temperature.
  
  

Hydrocarbons – alkanes and alkenes

• Hydrocarbons are typical simple molecular compounds.
  – They have low melting points and low boiling points.
  – They are insoluble in water.
• Alkanes are the simplest hydrocarbons.
• The alkanes form a homologous series of compounds with similar properties in which the formulas differ by For example, methane ethane and propane etc.
• Alkanes have strong bonds so they have few reactions.
  They do, however, combine with reactive non-metals like oxygen and chlorine.
  
  
  
• Hydrocarons, like ethane and other alkanes which have four single covalent bonds to all their carbon atoms, are described as saturated compounds.
• Hydrocarbons, like ethene, which contain a carbon-carbon double bond
  are called alkenes.
  
  
  
• Hydrocarbons, like ethene and other alkenes, which have double bonds between some carbon atoms are described as unsaturated compounds.