carbon compounds as fuels and feedstock

• what is a finite resource

  one that will run out/ cannot be replenished in a human lifetime
• crude oil is the remains of what

  remains of ancient biomass- mainly plankton that was buried in mud
• what is a hydrocarbon

  molecules made of hydrogen and carbon atoms only
• most of the hydrocarbons in crude oil are part of which homologous series

  alkanes
• general formula for alkanes

  Cn H2n+2
• first four members of the alkane fam

  methane

  ethane

  propane

  butane
• formula for the first four alkanes

  CH4 - methane

  C2H6 - ethane

  C3H8 - propane

  C4H10 - butane
• what is fractional distillation

  process which can separate the hydrocarbons into fractions each containing molecules with a similar number carbon atoms
• the fractions can be processed to produce f? and f?

  fuels and feedstock
• which industry is fuels and feedstock in

  petrochemical
• 4 useful material produced by the petrochemical industry

  solvents

  lubricants

  polymers

  detergents
• list from top to bottom the fuel produced from crude oil

  • liquified petroleum gas
  • petrol
  • kersene
  • diesel
  • heavy fuel oil
• how should fractional distillation work in terms of evaporation and condensation


  • mixture heated to 350 to vaporise oil
  • mixture enters the bottom of the fractionating column
  • column is hotter at the bottom and cooler at the top
  • the residue (long hydrocarbons) is a liquid and is removed via a tap
  • the remaining vapours move up, cool, condense at different heights depending on boiling point
  • each fraction can be collected at a different height
• boiling point of hydro carbons

  long chain = high boiling point because the bigger the molecule the stronger the forces of attraction- more energy needed to break
• viscosity of hydrocarbons

  • long chain = high viscosity
• flammability of hydrocarbons

  longer chain =lower flammability
• what is combustion

  process of burning fuels in oxygen for heat energy
• two types of combustion

  complete and incomplete
• equation for complete combustion of a hydrocarbon

  hydrocarbon + oxygen - water + carbon dioxide
• describe complete combustion

  when there is an excess of oxygen and the only products are water and carbon dioxide
• describe incomplete combustion

  there is limited oxygen and the products include carbon monoxide, carbon, some carbon dioxide and water
• what happens to the hydrogen and carbon during combustion

  oxidised
• what is cracking

  when hydrocarbons are broken down to produce smaller more usefulmolecules
• 2 cracking methods

  catalytic

  steam
• conditions for catalytic cracking

  • high temperature to vapourise hydrocarbon
  • a catalyst eg powdered aluminium oxide to split the hydrocarbons
• conditions for steam cracking

  • high temperature to vapourise the hydrocarbons
  • low pressure
• general cracking equation

  longer alkane- alkane + at least one alkene
• 2 uses of alkenes

  • polymers
  • starting material for producing other chemicals
• why are smaller alkanes useful

  higher demand for them eg petrol for cars
• general formula of alkenes

  Cn H2n
• how are alkenes different from alkanes

  alkenes contain a double bond
• how can you test for alkenes

  • alkenes are more reactive than alkanes and react with bromine water
  • add bromine water : if it goes from orange to colorless then it is an alkene - no reaction means alkane