Crude oil/fuel

• Crude oil


  Crude oil is a complex mixture of hydrocarbons ( a compound made of carbon and hydrogen only)
• Crude oil is formed over millions of years from the remains of marine organisms
• Formation of crude oil

  1. Tiny marine plants and animals died and were buried on the ocean floor.
  2. Dead marine animals were covered by layers of silt and sand.
  3. Over millions of years the remains get buried deeper and deeper.
  4. Heat pressure turned the remains into oil and natural gas
  5. We will drill down through layers of sand, silt and rock that contains oil and natural gas deposits
• Crude oil can be separated into simpler mixtures of hydrocarbons called fractions, by a process called fractional distillation
• The larger the number of carbon atoms in an element, the higher the boiling point
• Fractional distillation 


  Separates fractions based on their differing boiling points
• Fractional distillation method

  1. Crude oil is heated to become a mixture of gases
  2. The hot gaseous fractions rise up the fractionating column
  3. As the gases rise, they cool and condense
  4. Fractions with the lowest boiling points remain gases for longer (rise to top of column)
  5. Higher boiling point mixtures condense in higher temperatures at the bottom of the column
• As you go down the fractions:

  • Boiling points increase
  • Viscosity increases (become more sticky)
  • Colour change (colourless turns to yellow turns to brown)
  • Ease of ignition decreases (harder to set alight)
  • Flame changes from clean to slightly smoky to smoky
• Crude oil is non-renewable, so it is a finite resource.
• Fractions can be used for fuel, plastic and medicine
• Combustion


  Burning of any fuel requires oxygen, all combustion reactions are exothermic
• Hydrocarbons as fuels 


  Combusting hydrocarbons produce carbon dioxide and water

  hydrocarbon fuel + oxygen = carbon dioxide + water

  Balance the elements in order C,H,O
• Hydrogen as fuel


  When hydrogen is combusted, it produces water only (not carbon dioxide)

  Hydrogen is used as rocket fuel
• Advantages of hydrogen fuel

  • It is obtained from water which means that hydrogen is renewable
  • Only water is produced as a product so it does not contribute to global warming
  • Large amounts of energy is released in burning
  • Easy to ignite
• Disadvantages of hydrogen fuel

  • Storage requires bulky and heavy pressurised containers
  • Forms an explosive mixture with air
  • Obtained from water by electrolysis - requires electricity (contributing towards global warming/acid rain)
  • Electrolysis is expensive (lots of energy required)
• The fire triangle 


  Oxygen, fuel and heat
• Fire - to remove fuel

  • Turn off gas supply
  • Use fire breaks
• Fire - Remove heat

  Cool with water
• Fire - remove oxygen

  • Carbon dioxide extinguisher
  • Foam extinguisher
  • Sand
  • Fire blanket
• Water/foam should not be used on electrical fires as they could give shocks from electrical conduction
• Water should not be used for oil or petrol fire because the water boils causing the fire to spread
• Burning fuels experiment (1/3)

  1. Measure x mass of water into the conical flask.
  2. Clamp the flask at a suitable height so the spirit burner can be placed below it.
  3. Make sure the thermometer does not touch the bottom of the flask
  4. Record the initial temperature of water.
  5. Record mass of spirit burner (with lid) and fuel.
• Burning fuels experiment (2/3)

  6. Light spirit burner under conical flask.

  7. Heat the water for x amount of time and record the final temperature of the water.

  8. Calculate temperature increase

  9. Extinguish flame and record the mass of spirit burner (with lid)and fuel.

  10. Calculate mass of fuel burnt.

  11. Repeat using other fuels
• Burning fuels experiment - control variables (3/3)

  • Heating time
  • Volume of water
  • Distance between spirit burner and flask
  • type of spirit burner
• Alkanes

  • Saturated hydrocarbons - no c=c bonds only c-c bonds
  • The number of hydrogen atoms equals double the number of carbon atoms + 2
  • Carbon atoms always form 4 because they have 4 electrons in their outer shell (all single bonds)
• Isomers 


  Have the same molecular formula but a different structural formula
• The only reaction of alkanes is combustion because large amounts of energy are needed to break c-c bonds
• Alkenes

  • Unsaturated hydrocarbons - there is a double bond between two of the carbon atoms (c=c)
  • The number of hydrogen atoms equals double the number of carbon atoms
• Alkenes are reactive as they contain a double carbon bond which is easily broken.
• Test for Alkenes

  1. Bromine water is added to an alkene
  2. It turns from orange/brown to colourless
  3. No colour change with alkane
  4. Bromine water is used to test (rather than bromine) as it is safer and easier to handle
• Cracking

  Some of the fractions obtained from crude oil are very large (not very useful). The large hydrocarbons (alkanes) are broken down into smaller alkanes and more useful alkenes.

  • A high temperature and a catalyst are needed for cracking.
  • Does not produce the same products every time.
• Monomers


  Small, reactive, unsaturated molecules (c=c) which can join together to form a large, unreactive, saturated molecule called a polymer
• Additional Polymerisation 


  The c=c bond in a monomer breaks and each carbon atom takes back one electron each. a new c-c bond forms between the monomers using these electrons.

  A high temperature, pressure and a catalyst are needed to make each plastic (polymer)
• Uses of polymers

  • Poly(ethene) - bags, plastic bottles
  • Poly(propene) - ropes, crates
  • Poly(vinylchloride)or PVC - drain pipes, window frames
  • Poly(tetrafluoroethene) or PTFE - coating for non-stick pans
• Properties of plastic

  • Flexible
  • Strong
  • Good insulators
  • Resistant to corrosion
  • Waterproof
  • Low density
  • Take a long time to bio-degrade
• Plastic (environmental)

  • Take hundreds of years to bio-degrade
  • When burned releases toxic fumes/Carbon dioxide
  • Non-renewable (made of crude oil)
• Calorimetry


  The process used to measure the amount of heat energy released or absorbed during a chemical reaction
• Finite resource


  A resource which will one day run out
• Homologous series


  A series of compounds with the same functional group and similar chemical properties
• Monomer


  Small, short chain molecules which can join together to form a long chain polymer