Crude oil

• Crude oil


  Finite resource found in rocks, formed over millions of years from the remains of an ancient biomass consisting mainly of plankton that was buried in mud
• Hydrocarbons


  Compounds that contain hydrogen and carbon atoms only
• Mixture


  2 or more elements/compounds that are not chemically combined
• Crude oil is a feedstock for the petrochemical industry
• Fractional distillation


  1. The crude mixture is put in the bottom of the fractionating column and heated

  2. The hydrocarbons evaporate and rise up the column

  3. The further up the column, the cooler it is, so as hydrocarbons rise they eventually reach a fraction which is cool enough to cause them to condense back to a liquid

  4. Each fraction contains hydrocarbons of a similar chain length and can be tapped off

  5. The mixture left at the bottom of the fractionating column which does not evaporate at all is called bitumen
• As hydrocarbon chain length increases

  • Boiling point and melting point increases
  • Viscosity increases
  • Flammability decreases
  • Volatility decreases (harder to evaporate)
  • Their colour darkens
• Cracking


  Breaking down long chain hydrocarbons into shorter chains, which are more useful
• Cracking


  1. Heating the hydrocarbons to vaporise them

  2. Passing the vapours over a hot catalyst of silica or alumina

  3. Mixing the vapours with steam and heating to a very high temperature so that thermal decomposition reactions can occur
• Thermal decomposition


  Covalent bonds break, splitting long hydrocarbons into multiple smaller ones
• Alkenes


  Unsaturated hydrocarbons with the general formula CnH2n
• Alkenes are monomers that are used to make plastics
• Cracking decane


  Produces propene and heptane
• Economic importance of the oil industry

  • Oil companies set the price of oil so have an influence globally on the economy
  • Wars or internal crisis within a country that produces oil can affect the flow of oil to other countries 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 for the economy
• Environmental impact of the oil industry

  • Burning fossil fuels releases large amounts of carbon dioxide, a greenhouse gas, into the atmosphere, contributing towards 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 in the ocean result in the deaths of marine life and birds and are often dealt with by setting them alight
• Combustion of hydrocarbons

  1. Hydrocarbon + oxygen → carbon dioxide + water

  2. When there is insufficient oxygen the fuel will undergo incomplete combustion and as a result form carbon monoxide or carbon and water
• Combustion of ethanol


  C2H5OH + 3O2 → 2CO2 + 3H2O
• Combustion of hydrogen

  2H2 + O2 → 2H2O
• Advantages of using hydrogen as a fuel

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

  • Hydrogen is extremely flammable
  • Most of the hydrogen produced comes from fossil fuels or electrolysis so it still has a negative impact on the environment
  • Hard fuel to store and transport. Hydrogen must be cooled to very low temperatures so it liquifies and can be stored and transported. This is hard to do and the container must be very strong to withstand the high pressure inside it; it could potentially explode
• Fire triangle


  The 3 things needed for a fire to burn: oxygen, fuel, heat
• Preventing and putting out fires

  1. Removal of oxygen - fire extinguishers contain carbon dioxide that, when sprayed on the fire, push the oxygen away; fire blankets prevent new oxygen reaching the fire so it will eventually run out of oxygen and die out

  2. Removal of the fuel - fuel resistant materials can ensure any fires that start will quickly stop due to lack of fuel

  3. Removal of heat - water can be used to remove the heat in fires - however water can't be used on electrical fires or oil fires
• Calorimetry


  An experimental technique used to work out the energy released when burning a fuel
• Calorimetry method

  1. A known volume of water is added to a calorimeter and a thermometer is used to measure and record the start temperature

  2. A known mass of fuel is then burnt beneath the calorimeter so the heat given off heats the water

  3. The maximum temperature the water reaches is recorded and the final mass of the fuel is found so the mass of fuel that was burned can be calculated

  4. The energy per gram of fuel can then be calculated
• The energy per gram of fuel = (mass of water in grams x 4.2 x temperature change) / mass of fuel burned
• Hydrocarbons

  Contain hydrogen and carbon atoms only
• Alkanes

  Saturated hydrocarbons with the general formula CnH2n+2
• Prefixes in naming compounds

  Meth- (1C), Eth- (2C), Prop- (3C), But- (4C), Pent- (5C), Hex- (6C), etc.
• Suffixes in naming compounds

  Alkanes - ane (C-C), Alkenes - ene (C=C), Alcohols - ol (OH), Carboxylic acids - anoic acid (-COOH)
• IUPAC name


  The formal name of the compound
• Molecular formula


  Gives the number and type of each type of atom
• Structural formula

  Gives the number and type of each type of atom and their arrangement in the molecule
• Isomerism

  When 2 compounds have the same molecular formula but their structures differ
• Types of isomerism


  • Chain - the main carbon chain differs in length
  • Position - in alkenes the position of double bond(s) in the molecules can differ
• Naming complex alkanes and alkenes

  1. Locate the longest unbroken 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
• Examples of isomerism


  • Chain - the main carbon chain differs in length
  • Position - in alkenes the position of double bond(s) in the molecules can differ
• Naming complex alkenes and alkanes

  1. Locate the longest unbroken 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

  5. If there are multiple groups of the same functional groups the prefixes di-, tri-, tetra-, penta- etc are used
• Addition reactions


  • Reactions in which two or more molecules combine to form a larger one with no other products
  • Alkenes have a double bond which makes them more reactive than alkanes
  • Alkenes undergo addition reactions with hydrogen and bromine
• Addition reactions with hydrogen


  The double bonds open up and bond to hydrogen, forming an alkane