Crude Oil, Fuels and Organic Chemistry

• Crude oil


  A finite resource found in rocks, formed over millions of years from the remains of simple marine organisms. It contains a complex mixture of hydrocarbons.
• Fractional distillation of crude oil

  1. The crude mixture is put into the fractionating column at the bottom and heated

  2. The hydrocarbons evaporate and rise up the column

  3. As the hydrocarbons rise, they eventually reach a fraction which is cool enough for them to condense back into a liquid

  4. The mixture left at the bottom, which does not evaporate at all, is called bitumen
• Fractions


  Contain mixtures of hydrocarbons (alkanes) with similar boiling points
• Trends in properties of fractions with increasing chain length


  • Boiling and melting point increases
  • Viscosity increases
  • Flammability increases
  • Volatility increases
  • Their colour darkens
  • Their usefulness as fuels decreases
• Economic importance of the oil industry

  • Oil companies set the price of oil so there is an influence globally on the economy - it can be hard for poorer countries to buy oil
  • Wars or internal crisis within a country that produces oil can affect the flow of oil to other countries which they sell to
• Political importance of the oil industry

  • Countries that are large producers of oil can essentially cut off oil supplies to other countries
  • This is used as a political tool
• Social impact of the oil industry

  • The oil industry supplies jobs and money to the economy
• Environmental impacts of the oil industry

  • Burning fossil fuels releases large amounts of carbon dioxide, a greenhouse gas, into the atmosphere, contributing to global warming and climate change
  • The building of power stations and the process of drilling for oil causes damage to the landscape and loss of habitats
  • Oil spillages into the ocean result in the deaths of marine life and birds and are often dealt with by setting them alight
• Combustion reactions of hydrocarbons

  1. When hydrocarbons burn in plenty of oxygen it will combust as follows: hydrocarbon + oxygen carbon dioxide + water

  2. When hydrocarbons burn with insufficient oxygen it will combust as follows: hydrocarbon + oxygen carbon monoxide + water
• Calorimetry


  An experimental technique used to work out the energy released when burning a fuel
• Method of calorimetry


  1. A known volume of water is added to a calorimeter and the temperature is recorded

  2. A known mass of fuel is burnt beneath the calorimeter

  3. The maximum temperature of the water and the final mass of the fuel is recorded

  4. Energy released (Joules)= mass of water (g) x temp change x 4.2

  5. Energy per gram of fuel = energy released (J) / mass of fuel burned (g)
• Combustion reaction of hydrogen


  Hydrogen burns in oxygen and forms water
• Uses of hydrogen


  • Hydrogen is used as fuel in rockets and some cars
• Advantages of using hydrogen as a fuel

  • No greenhouse gases are produced in the combustion of hydrogen
  • An alternative fuel option as current fuels are running out
• Disadvantages of using hydrogen as a fuel

  • Hydrogen is extremely flammable
  • Most of hydrogen produced comes from fossil fuels or electrolysis so it still has a negative impact on the environment
  • Hard to store and transport - must be cooled to very low temperatures so it liquifies for storage and transport
• Fire triangle


  A symbol that contains 3 things needed for a fire to burn: oxygen, fuel and heat. Removing any of these will cause the fire to stop burning, so knowledge of the fire triangle can be used to prevent and put out fires.
• Hydrocarbon cracking


  Breaking long chain hydrocarbons down into shorter and more useful chains
• Products of hydrocarbon cracking

  • Alkanes and unsaturated hydrocarbons called alkenes
  • Alkenes are monomers that are used to make plastics
• General formula of alkanes


  Cn H2n +2 where n is the number of carbon atoms in the molecule
• General formula of alkenes

  Cn H2n where n is the number of carbon atoms in the molecule
• Simple alkanes


  • Methane, CH4, CH4
  • Ethane, C2H6, CH3CH3
  • Propane, C3H8, CH3CH2CH3
  • Butane, C4H10, CH3CH2CH2CH3
• Simple alkenes


  • Ethene, C2H4, CH2=CH2
  • Propene, C3H6, CH2=CHCH3
  • Butene, C4H8, CH2=CHCH2CH3
• Isomerism


  When two compounds have the same molecular formula (same number and type of each atom) but their structures differ in some way
• Isomerism in alkanes


  The main carbon chain length differs but the molecule still has the same number of carbon atoms
• Isomerism in alkenes


  The position of the double bond in the molecules can differ but the molecular structure stays the same
• Naming complex alkanes and alkenes

  1. Locate the longest continuous linear chain of carbon atoms

  2. Number the carbon atoms from the end closest to a functional group or branch point

  3. Alphabetically list the functional groups attached to the carbon chain and state the carbon number the group is attached to

  4. For double bonds, count the position of the double bond by counting bonds not carbon atoms
• Addition reactions


  Reactions in which two or more reactants combine to form a single product
• How to name complex alkanes and alkenes

  1. Locate the longest continuous linear chain of carbon atoms

  2. Number the carbon atoms from the end closest to a functional group or branch point

  3. Alphabetically list the functional groups attached to the carbon chain and state the carbon number the group is attached to

  4. For double bonds, count the position of the double bond by counting bonds not carbon atoms
• Addition reactions


  Reactions in which two or more molecules combine to form a larger one with no other products
• Test for alkenes


  Bromine water is an orange solution and when shaken with an alkene the bromine water will decolourise as the bromine reacts with the alkene to form substituted alkanes - this is an addition reaction
• Addition polymerisation


  • Alkenes can be used to make polymers
  • Polymers are large molecules made up of repeating units called monomers
  • Alkenes can be polymerised because they have double bonds that open up to connect to other alkene monomers in a chain
  • E.g. polyethene is formed from ethene monomers
• Uses of poly(propene)


  • Plastic for cars
  • Packaging
  • Textiles
• Uses of polyvinyl chloride (PVC)

  • Water pipes
  • Electrical wires
  • Window panes
  • Medical tubing and IV bags
• Uses of poly(tetrafluoroethene) (PTFE)

  • Coating non-stick pans
  • Nail polishes
  • Coating hair straighteners and curlers
• General properties of polymers

  • Thermosoftening polymers melt when heated and can be remoulded and reshaped
  • Thermosetting polymers do not melt when heated
  • High-density polymers tend to be harder and stronger than low-density polymers
• Environmental issues relating to the disposal of plastics

  • Plastics are non-biodegradable
  • Increasing pressure on landfill sites for waste disposal
• Methods for disposing plastics

  • Landfill sites
  • Incineration disposal - however this releases carbon dioxide, a greenhouse gas
  • Recycling - this manages the other issues of disposal, provides jobs and helps preserve the non-renewable source of crude oil
• How ethanol is produced

  1. The fermentation of sugar using yeast - the enzymes in yeast catalyse the reaction

  2. Glucose → Ethanol + Carbon Dioxide
• Test for alcohol


  • Add a few drops of sulfuric acid and potassium dichromate solution to the sample
  • Gently heat
  • If alcohol is present the solution will change from orange to green
• Uses of ethanol


  • Found in alcoholic drinks
  • As a solvent - it dissolves a large number of substances easily
  • As a fuel