Cracking of crude Oil

• Crude oil has various uses important in modern life
• Uses of crude oil

  • Heavy fuel oil
  • LPD (liquid petroleum gas)
  • Fuel for transport
  • Petrochemical industry
  • Products like polymers, solvents, lubricants
• Crude oil provides the fuel for most modern transport including cars, trains, and planes
• Petcochemical industry

  Uses some hydrocarbons from crude oil as feedstock for various products
• All products from crude oil are examples of organic compounds made of carbon atoms
• Homologous series

  Groups of compounds with similar properties formed by alkanes and alkenes
• Cracking

  1. Splitting up long-chain hydrocarbons

  2. Producing smaller, more useful hydrocarbons
• Short-chain hydrocarbons are flammable and make good fuels
• Long-chain hydrocarbons form thick, gloopy liquids that aren't as useful
• Some products of cracking are useful as fuels, e.g. petrol and paraffin
• Alkenes

  More reactive than alkanes and used as starting materials for making other compounds
• Bromine water test for alkenes

  1. Add to alkane - no reaction, stays bright orange

  2. Add to alkene - reacts and decolourises
• Methods of cracking

  1. Thermal decomposition reaction

  2. Heat long-chain hydrocarbons to vaporise

  3. Pass vapour over hot powdered aluminium oxide catalyst

  4. Long-chain molecules split on catalyst surface

  5. Steam cracking by mixing with steam and heating
• Cracking is a thermal decomposition reaction that breaks molecules down by heating
• Steps of cracking

  1. Heat long-chain hydrocarbons to vaporise

  2. Pass vapour over catalyst

  3. Molecules split apart on catalyst surface

  4. Vaporise, mix with steam, and heat for steam cracking
• You need to be able to balance chemical equations for cracking