Chemistry Y9 C1

• Crude oil contains a mixture of different compounds that have many uses. Mostly we separate these compounds to use as petrol or diesel.
• Crude oil


  A fossil fuel. It is a liquid that we find in porous rocks and it is a finite resource

  
• Finite means that we are using it up faster than it can be made and one day we are going to run out!
• Porous rock


  A rock with many holes in it that allows air and water to travel through
• How crude oil was formed


  Crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried in mud. Over millions of years, the remains were buried deeper and deeper. Heat and pressure turned it into oil and natural gas

  
• Different compounds have different properties
• We can separate the compounds based on their different properties
• Fractional distillation


  A process that separates crude oil into its different fractions based on their boiling points
• Fractions of crude oil


  • Refinery gases
  • Gasoline
  • Naptha
  • Kerosene
  • Diesel fuels
  • Fuel oil
  • Bitumen

  
• Crude oil consists of large molecules called hydrocarbons
• Hydrocarbon


  A molecule that contains only hydrogen and carbon atoms, joined together by covalent bonds
• Most of the compounds in crude oil are hydrocarbons
• Examples of hydrocarbons


  • Methane, CH4
  • Ethyne, C2H2
• A hydrocarbon contains only hydrogen and carbon atoms, joined together by chemical bonds
• Alkanes


  • As the number of carbons increases, the boiling point increases, the viscosity increases, and the flammability decreases
• Intermolecular forces


  The forces between hydrocarbon molecules that cause the trends in physical properties
• Methane has a lower boiling point than hexane due to weaker intermolecular forces
• Bitumen is more viscous than petrol due to its longer hydrocarbon chains
• First 7 alkanes


  • Methane
  • Ethane
  • Propane
  • Butane
  • Pentane
  • Hexane
  • Heptane
• Hydrocarbons are a type of molecule that contains only hydrogen and carbon atoms
• Crude oil is a non-renewable energy source because it is being used up faster than it can be formed
• Alkenes


  Unsaturated hydrocarbons that contain at least one double covalent bond
• Testing for alkenes vs alkanes

  Alkenes decolourise bromine water, alkanes do not
• Polymer


  A very large molecule made when hundreds of monomers join together to form long chains
• Plastics are synthetic polymers that can be shaped by heat or pressure
• Addition polymerization


  The process by which polymers like polyethene are made, where many monomers are added together
• Polymers are made from alkenes, which contain at least one double covalent bond
• Shorthand formula for polymers


  Shows a repeating unit in brackets with 'n' to indicate a very large number of repeats
• The monomer for polyvinylchloride (PVC) is a molecule with two carbon atoms joined by a double bond
• Properties of plastics


  • They do not conduct electricity and are poor conductors of heat, they are unreactive - not affected by water, air or many chemicals
• The unreactivity of plastics is both useful and problematic - it makes them durable but also means they persist in the environment for a long time
• Methods of disposing of waste plastics


  • Landfill
  • Incineration (burning)
  • Recycling
• Most plastics cannot be decomposed by micro-organisms and will remain in landfill sites for thousands of years without rotting
• Plastic products carry a symbol that shows which type of polymer they are made from, to aid recycling
• Usually, the only types of plastic to be recycled are PET, PVC and HDPE
• If different polymers are mixed together during recycling, it can reduce the quality and value of the final recycled plastic
• Landfill is a convenient method of waste disposal but it is only designed to bury rubbish, not to break it down
• Most plastics are made up of tightly bonded molecules that cannot be decomposed by micro-organisms. These will remain buried at landfill sites for thousands of years without rotting
• Plastic recycling symbol


  Shows which type of polymer the plastic is made from
• Many plastic items look and/or feel similar to each other but they are actually made from different materials, e.g. margarine tubs (polystyrene) and plant pots (polypropene)