Organic Chemistry

• Hydrocarbons only contain which two elements:

  • hydrogen
  • carbon
• the 4 alkanes:

  • methane
  • ethane
  • propane
  • butane

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• alkane:

  • METHANE

  
• alkane:

  • ETHANE

  
• alkane:

  • PROPANE

  
• alkane:

  • BUTANE

  
• rules for alkanes = CnH2n+2
• As the chain length (number of carbon atoms) of alkanes increases they become:

  • more viscous
  • more flammable
  • higher boiling point
• crude oil:

  • a mixture of hydrocarbons at different lengths
• combustion:

  • burning fuel with the presence of oxygen
• complete combustion of hydrocarbons:

  • hydrocarbon + oxygen -> carbon dioxide + water
  • this occurs when there is a large supply of oxygen
• incomplete combustion:

  • hydrocarbon + oxygen -> carbon monoxide + water
  • this occurs when there is no oxygen
• pollutants:

  • carbon dioxide
  • particulates
  • carbon monoxide
• carbon dioxide as a pollutant:

  • greenhouse gas
  • traps the suns energy in our atmosphere
  • causes the atmosphere to heat up
  • leads to global warming
• particulates as a pollutant:

  • (soots) are tiny solid particles containing carbon and unburnt hydrocarbons
  • these can be carried in the air
  • causes global dimming
  • causes asthma
• carbon monoxide as a pollutant:

  • poisonous gas
  • the silent killer (odourless and colourless)
  • stops the red blood cells by reducing the amount of oxygen transports in red blood cells
• cracking:

  • the splitting of a long chain alkane to produce a shorter alkane and alkenes
• catalysts:

  • speeds up a chemical reaction without being used up
• thermal decomposition:

  • a chemical reaction where heat is a reactant
• thermal decomposition:

  alkene:

  • bromine water changes from orange to colourless

  alkane:

  • bromine water remains orange
• What is crude oil primarily composed of?

  A mixture of hydrocarbons
• Why is crude oil heated in fractional distillation?

  To separate hydrocarbons based on boiling points
• What happens to the gaseous hydrocarbons in the fractionating column?

  They rise up the column
• Why do hot gaseous hydrocarbons rise in the fractionating column?

  Because hot gas rises
• What occurs as hydrocarbons rise in the fractionating column?

  They cool down
• Where is the fractionating column cooler?

  At the top
• When do hydrocarbons condense in the fractionating column?

  When they cool below their boiling point
• What happens to liquid hydrocarbons after they condense?

  They collect in trays and drain out
• Where do longer chain hydrocarbons condense in the fractionating column?

  At the bottom
• Why do longer chain hydrocarbons condense at the bottom?

  Because they have high boiling points
• Where do shorter chain hydrocarbons condense in the fractionating column?

  At the top
• Why do shorter chain hydrocarbons condense at the top?

  Because they have much lower boiling points