Crude Oil

• Describe how crude oil is formed

  • plankton
  • buried in mud
  • over millions of years
• What type of resource is crude oil?

  • finite resource
  • found in rocks
• What does finite resource mean?

  • eventually will run out
  • being used at a rate faster than it is being replenished
• What is crude oil?

  • a mixture of hydrocarbons
  • hydrocarbons = compounds that contain hydrogen and carbon atoms only
• Alkanes

  • hydrocarbons
  • saturated
• Most hydrocarbons in crude oil

  • alkanes
• General formula of alkanes

  • CnH2n+2
• Boiling points : Substances in crude oil have

  • different boiling points
• Crude oil is separated by

  • Fractional distillation
• How do you know C5H12 is an alkane?

  • matches general formula
  • CnH2n+2
• First four members of alkanes

  • methane
  • ethane
  • propane
  • butane
• Mice

  • mice = methane
  • eat = ethane
  • plastic = propane
  • bags = butane
• Describe how crude oil is separated into fractions using fractional distillation

  • crude oil is heated
  • to evaporate / vaporise the hydrocarbons
  • the column is hotter at the bottom
  • fractions condense
  • at their different boiling points
• Why are fractions processed?

  
  

  
  

  • produce fuels
  • feedstock
  • for petrochemical industry
• Fuels produced from crude oil : modern lifestyle


  • petrol
  • kerosene
• Useful materials produced by crude oil : modern lifestyle


  • lubricants
  • detergents
  • solvents
• Crude oil itself

  • useless
• Homologous series

  • families of similar compounds
  • in this case, hydrocarbons
  • same general formula
• Alkanes form a ________ series

  • homologous
• Fractional distillation

  1. evaporation
  2. condensation
• Saturated alkanes 


  • form single c-c bonds
• Combustion of hydrocarbons


  • carbon and oxygen are oxidised
• Complete combustion

  • plentiful supply of oxygen in air
• Products of complete combustion


  • carbon dioxide
  • water (vapour)
• Complete combustion word equation

  hydrocarbon + oxygen ---> carbon dioxide + water
• Incomplete combustion

  • limited supply of oxygen in air
  • produces carbon monoxide
  • particulates of carbon (soot)
• Properties of hydrocarbons that rely on molecular size

  • flammability
  • viscosity
  • boiling point
• Boiling point : As hydrocarbon chain length increases..

  • Boiling point increases
  • (fractions towards the bottom of the column)
• Viscosity : As hydrocarbon chain length increases..

  • Viscosity increases
• Higher viscosity

  • thicker
• Low viscosity

  • runny
• Flammability : As the hydrocarbon chain length increases..

  • flammability decreases
  • (fractions towards the bottom of the column)
• Why do short(er)-chain hydrocarbons have lower boiling points?

  • smaller molecule
  • weak intermolecular forces
  • less energy needed to break bonds / overcome forces
• Explain why C8H18 has a lower boiling point than C14H30

  • C8H18 = smaller molecule
  • weak intermolecular forces
  • less energy needed to overcome forces
• Fractionating column : As hydrocarbon chain length increases..

  • volatility decreases
  • how easy it is to evaporate
• Least volatile fraction

  • fraction with the highest boiling point
  • bottom of the fractionating column
• Fractions with the lowest boiling point


  • gas at room temp.
  • stored as bottled gas.
• Why do the fractions separate at different temperatures?

  • condense at different boiling points
• How can you tell that each of the fractions is a mixture?


  • range of boiling points
• Compare ethane and ethene (6)

  • Refer to structure bonding, reactions 


  Both are hydrocarbons

  Both contain two carbon atoms

  Both have covalent bonds

  Ethane contains a single carbon-carbon bond but ethene contains a double carbon-carbon bond

  Ethene decolourises bromine water but ethane does not decolourise bromine water