Alkanes

• How many isomers does butane have?

  Two
• How does the number of isomers change with carbon addition?

  It increases with every carbon added
• Do methane, propane, and ethane have isomers?

  No
• Are alkanes polar or non-polar?

  They are almost non-polar
• What are the intermolecular forces in alkanes called?

  Van der Waals forces
• How effective are Van der Waals forces in alkanes?

  They are weak intermolecular forces
• Do branched chain alkanes have higher or lower boiling points?

  Lower boiling points
• Why are alkanes insoluble in water?

  Water's hydrogen bonds are stronger
• What are alkanes used as in chemistry?

  Feedstock
• Describe the process of fractional distillation.

  • Crude oil is heated in a furnace
  • Mixture of liquid and vapor enters a cooler tower
  • Vapors rise and condense on trays
  • Liquids are piped off
  • Shorter chains condense higher due to lower BP
  • Thick bitumen collects at the bottom
• What are the temperatures for thermal cracking?

  700-1200K
• What pressure is used in thermal cracking?

  7000 kPa
• What happens during thermal cracking?

  Carbon-carbon bonds break, forming free radicals
• What is produced during thermal cracking?

  A high proportion of alkenes
• What conditions are required for catalytic cracking?

  Lower temperatures and pressures
• What is a zeolite?

  A material with a honeycomb structure
• What does catalytic cracking produce?

  A high proportion of branched alkanes
• What are the polluting products from alkane combustion?

  • Carbon monoxide (poisonous)
  • Nitrogen oxides (acid rain)
  • Sulfur dioxide (acid rain)
  • Particulates (lung cancer)
  • Unburnt hydrocarbons (greenhouse gases)
  • Carbon dioxide (greenhouse gas)
  • Water vapor (greenhouse gas)
• What is the equation for sulfur forming acid rain?

  SO2 + 1/2O2 + H2O → H2SO4
• What is the process of removing sulfur called?

  Flue gas desulfurisation
• What metals are used in catalytic converters?

  Platinum, palladium, rhodium
• What happens in a catalytic converter?

  2CO + 2NO → N2 + 2CO2
• What is a necessary condition for free radical substitution?

  UV light
• Why are chlorine free radicals formed from CFCs?

  C-Cl bond breaks homolytically in UV light
• What are the equations for chlorine attacking ozone?

  Cl . + O3 → ClO. + O2
• Why do we crack alkanes?

  Shorter chain alkanes are economically more valuable and useful
• Why can sulfur dioxide be removed from flue gases using calcium oxide?

  Because sulfur dioxide is acidic and calcium oxide is basic