7.1. Carbon Compounds as Fuels and Feedstock

• What is crude oil classified as?

  A finite resource found in rocks
• What is crude oil primarily composed of?

  Remains of ancient biomass mainly consisting of plankton
• What type of mixture is crude oil?

  A mixture of a very large number of compounds
• How can the substances in crude oil be separated?

  By physical methods including distillation
• What are hydrocarbons primarily made up of?

  Molecules made up of hydrogen and carbon only
• What is the general formula of alkanes?

  C$_n$H$_{2n+2}$
• What are the first four alkanes?

  • Methane
  • Ethane
  • Propane
  • Butane
• How does fractional distillation work?

  Oil is heated in a fractionating column and evaporates at different temperatures
• What does the fractionating column do with the hydrocarbons?

  Separates them into fractions with similar numbers of carbon atoms
• How is the fractionating column operated?

  Heated crude oil is piped in at the bottom and vapor rises up the column
• What are some fuels produced from crude oil?

  Petrol, diesel oil, kerosene, heavy fuel oil, and liquefied petroleum gases
• What materials does the petrochemical industry produce?

  Solvents, lubricants, polymers, and detergents
• Why do carbon atoms form a vast array of compounds?

  Due to their ability to form families of similar compounds
• How do the properties of hydrocarbons depend on their molecular size?

  Some properties influence their use as fuels
• What happens to the viscosity of hydrocarbons as their molecules get shorter?

  They become less viscous
• How does the boiling point of hydrocarbons change with molecular size?

  Shorter molecules have a lower boiling point
• What is the relationship between molecular size and flammability of hydrocarbons?

  Shorter molecules are more flammable
• Why are hydrocarbons burnt?

  To produce energy through oxidation
• What is the general reaction for burning hydrocarbons (combustion)?


  Hydrocarbon -> carbon dioxide + water
• What is cracking?

  Heating hydrocarbons to produce smaller, more useful molecules
• What are the two methods of cracking hydrocarbons?

  • Catalytic cracking
  • Steam cracking
• What is the general formula for alkenes?

  C$_n$H$_{2n}$
• What are the first two alkenes?

  Ethene and propene
• How do alkenes react with bromine water?

  They turn bromine water from brown-orange to colourless
• Why are alkenes more reactive than alkanes?

  Because an alkene's double bond makes them more reactive
• What are some uses of alkenes?

  Producing other chemicals such as polymers
• Why are some products made from cracking useful as fuels?

  They have shorter chains than the original alkanes, making them more flammable
• What must be ensured in the equations for cracking hydrocarbons?

  The same number of carbons and hydrogens on each side of the equation
• How would you determine the missing product in the cracking equation C$_6H_{14}$ → C$_2H_{4}$ + ?


  Calculate the remaining carbons and hydrogens
• What is the missing product if C$_6H_{14}$ → C$_2H_{4}$ + ?


  The missing product is C$_4H_{10}$