topic 8 fuels and earthscience

• crude oi is a mixture of hydrocarbons that have not been refined
• crude oil is remains of plankton and other living material buried in mud million of years ago
• crude oil is a finite resource What is that?

  Non-renewable
• Hydrocarbons are compounds made from only carbon and hydrogen atoms.
• The hydrocarbon molecules in crude oil are made up of carbon atoms in chains or rings.
• What are most substances used is crude oil for?

  fuel
• Examples of these fuels are petrol, diesel oil, kerosene, heavy fuel oil and liquefied petroleum gas.
• substances in crude oil are also used for

  • feedstocks
  • petrochemical industry
  • raw materials to make chemical products for everd day life
  •  some fractions are used to make solvents, lubricants, detergents and polymers.
• what are the different groups of hydrocarbons?(and what do they all have)

  fractions they all have a similar number of carbon atoms.
• The mixture of hydrocarbons in crude oil can be separated to form useful products.
• How do you separate fractions?

  fractional distillation
• Fractional distillation .

  1.  evaporate the crude oil by heating it.

  This causes most of the hydrocarbons to evaporate and rise up the fractional distillation column.
• 2. The column is hotter at the bottom and cooler at the top.

  Short hydrocarbons have lower boiling points.

  As a result, short hydrocarbons condense near the top of the column where it is cooler.

  Long hydrocarbons have higher boiling points.

  As a result, long hydrocarbons condense nearer the bottom of the column.
• main fractions

  1. refinery gases(fraction containing shortest hydrocarbons)
  2. gasoline(petrol)
  3. kerosene
  4. Diesel oil
  5. fuel oil
  6. Bitumen
• what is gases used for

  domestic heating and cooking.
• What is petrol used for?

  fuel for cars
• What is kerosene used for?

  fuel for aircraft
• What is diesel oil used for?


   fuel for some cars and trains.
• What is fuel oil used for?


  fuel for large ships and in some power stations.
• What is Bitumen (fraction containing the longest hydrocarbons) used for?

  surface roads and roofs.
• In crude oil, most of the hydrocarbons are a type called alkanes.
• What are alkanes?


  Alkanes are hydrocarbons with the general formula CnH2n+2.
• All the carbon and hydrogen atoms are connected by single covalent bonds.
• The hydrocarbons in different fractions have different properties and the size of  hydrocarbon affects its properties.
• hydrocarbon properties are:

  • Boiling point 
  • Viscosity is a measure of how sticky (or thick) a liquid is.
  • Ease of ignition is a measure of how easy it is to burn something.
• The differences in properties explain why different fractions of hydrocarbons have different uses.
• shorter hydrocarbons

  • lower boiling points,
  • lower viscosity
  • high flammability.
  •  contain the fewest carbon and hydrogen atoms.
  • found in the gases fraction.
• Longer hydrocarbons

  • higher boiling points
  • higher viscosity
  • low flammability
  • found in the bitumen fraction at the bottom of the column.
  • contain the most carbon and hydrogen atoms.
• What is a homologous series?

  "family" of organic compounds with similar properties and common trends.  also a gradual change in the physical properties of compounds
• The compounds in a homologous series have the same general formula.

  For example, the general formula for alkanes is CnH2n+2.

  Each compound in a homologous series differs from its neighbouring compounds by 1 CH2 group.
• The compounds in a homologous series have the same general formula.
• Why do Compounds in a homolgous series have  similar reactions?

   similar chemical properties
• combustion = burning
• Why are hydrocarbons useful as fuel?

  When hydrocarbons combust, energy is released.
• how does complete combustion occur?

  if there is plenty of oxygen present
• What is the equation of complete combustion

  hydrocarbon + oxygen -> carbon dioxide + water
• Why does incomplete combustion happen?

  If there's not enough oxygen for complete combustion
• Why does Incomplete combustion produces carbon (soot) and carbon monoxide as well as carbon dioxide and water.?

  not enough oxygen available to combine with all of the carbon in the fuel.
• carbon monoxide:

  • toxic to humans(lowers amount of oxygen you can carry because it blends with haemoglobin in red blood cell)
  • hard to detect (colourless and odourless)
  • breathe in you will die/lose conscious
• soot:

  • blacken tree and building
  • limits amount of light reaching sunlight
  • causes lung and heart problems