Alkanes

• Catalytic Converter


  A device in a car which reduces the amount of emissions from an internal combustion engine. Uses metals like platinum and rhodium as the heterogenous catalyst. Catalyst is mounted on a ceramic honeycomb which maximises the surface area
• catalytic cracking 


  type of cracking which takes place at a slight pressure, high temperature and in the presence of a zeolite catalyst .
• combustion of alkanes

  releases energy. C and H in the fuels are oxidised. the alkanes can undergo complete or incomplete combustion, water and CO2 are the only products of complete combustion. CO and C particulates can be produced in incomplete combustion
• cracking

  a process which involves breaking C-C bonds in alkanes to produce shorter chained alkanes and alkenes
• Crude oil


  A finite resource found in rocks. The remains of ancient biomass consisting of mainly plankton that was buried in mud. They are mostly hydrocarbons
• fractional distillation 


  a method of separating a mixture of substances according to their different boiling points. commonly used to separate crude oil
• hydrocarbons


  compounds made up of carbon and hydrogen atoms only
• saturated 


  organic compounds where all the C-C atoms are single bonds
• thermal cracking


  type of cracking which takes place at high temperature and high pressure. produces a high percentage of alkenes
• 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 fractional distillation of crude oil?

  1. Vapourise the mixture
  2. Feed into the fractionating column
  3. Vapours rise, cool, and condense
  4. Siphon off products 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 column?

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

  They are broken down via cracking
• What is the purpose of cracking in hydrocarbons?

  To form 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)
  • Slight pressure
  • Uses zeolite catalyst
  • Produces aromatic compounds and motor fuels
• Why are alkanes considered good fuels?

  They release a lot of energy when burned
• What products are formed during 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 product of incomplete combustion?

  Carbon monoxide
• What is the role of catalytic converters in combustion systems?

  To convert harmful products into stable ones
• What catalyst is used in catalytic converters?


  Rhodium
• What are carbon particulates and their impact?

  Small fragments causing respiratory problems
• What is flue gas desulfurisation used for?

  To remove sulfur impurities from waste products
• What chemicals are used in flue gas desulfurisation?

  Calcium oxide and gypsum
• What environmental issues can pollutants contribute to?


  Global warming, acid rain, and health issues
• How do alkanes react with halogens?

  In the presence of UV light to form halogenoalkanes
• What are the steps in the chlorination of alkanes?

  1. Initiation: Halogen bonds break, forming free radicals
  2. Propagation: Hydrogen is replaced, regenerating the Cl• radical
  3. Termination: Two radicals join to form a stable product

  
• What is the significance of free radicals in the chlorination process?

  They initiate a series of chain reactions

  
• How can the conditions of the chlorination reaction be altered?

  To favor termination and limit substitutions