Alkanes

• What is crude oil primarily composed of?

  A mixture of different hydrocarbons
• How does fractional distillation separate crude oil?

  By utilizing different boiling points of hydrocarbons

  
• What are the steps involved in the fractional distillation of crude oil?

  1. The mixture is vaporized and fed into the fractionating column.
  2. Vapors rise, cool, and condense.
  3. Products are siphoned off for different uses.

  
• Where are products with short carbon chains collected in the fractionating column?

  At the top of the column
• Why do products with long carbon chains condense at the bottom of the fractionating column?

  They have higher boiling points
• What happens to the compounds collected from the fractionating column?

  They are broken down further via cracking
• What is the purpose of cracking in the context of alkanes?

  To break down longer carbon chains into smaller, more useful molecules
• What are the two main types of cracking and their characteristics?

  1. Thermal Cracking:

  • High temperatures (~1200 K)
  • High pressures (~7000 kPa)
  • Produces alkanes and alkenes

  1. Catalytic Cracking:

  • Lower temperatures (~720 K)
  • Normal pressure
  • Requires a zeolite catalyst
  • Produces aromatic compounds
• Why are alkanes considered good fuels?

  They release a lot of energy when burned
• What are the products of complete combustion of alkanes?

  Carbon dioxide and water
• What occurs during incomplete combustion of alkanes?

  Carbon monoxide is produced alongside water

  
• What is a toxic gaseous product of alkane combustion?

  Carbon monoxide
• How do catalytic converters help reduce harmful emissions?

  They convert harmful products into more stable products like CO2 or H2O

  
• What catalyst is used in catalytic converters?

  Rhodium
• What are carbon particulates and why are they a concern?

  Small fragments of unburned hydrocarbons that can cause respiratory problems
• What is flue gas desulfurization used for?

  To remove sulfur impurities from waste products
• What are the consequences of untreated pollutants from alkane combustion?

  • Contribute to global warming
  • Cause acid rain
  • Lead to health issues in humans
• What happens when alkanes react with halogens in the presence of UV light?

  They produce halogenoalkanes through a series of reactions

  
• What are the three steps in the reaction of alkanes with halogens?

  1. Initiation: Halogen bonds are broken.
  2. Propagation: A hydrogen is replaced, and a Cl• radical is reformed.
  3. Termination: Two radicals join to form a stable product.
• What is the role of free radicals in the chlorination of alkanes?

  They are reactive intermediates that initiate the chain reaction
• How can the conditions of the chlorination reaction be altered?

  To favor the termination step and limit the number of substitutions