alkanes

• What are structural isomers?

  Structural isomers are molecules that have the same molecular formula but different structural formulae.
• At room temperature and pressure, the first four members of the alkanes are all gases but the first four alcohols are all liquids. Why?


  alkanes have London dispersion forces

  alcohols have hydrogen bonds (O-H) as well as London dispersion forces

  hydrogen bonds are stronger than the LDF in alkanes, thus more energy is required to break the hydrogen bonds than the LDF and to change state
• What are the conditions for catalytic cracking?

  450 degrees

  slight pressures

  zeolite catalysts
• What are catalytic converters?

  A device in cars that removes CO, NOx and unburned hydrocarbons from exhaust gases, turning them into CO2, N2 & H2O
• What is a petroleum fraction?

  A mixture of hydrocarbons with a similar chain length and similar boiling point
• What is the fractional distillation process?

  crude oil is heated until (mostly) vaporised

  • passed into a fractionating tower that is cooler at the top than the bottom
  • liquid fractions are run off at the bottom
  • vapours rise up the column (via trays and bubble caps) and condense when the temperature is below their boiling point
  • shortest chain hydrocarbons condense at the top as they have the lowest boiling points
• What is cracking?

  the conversion of large hydrocarbons to smaller, more useful hydrocarbon molecules, by breaking C-C bonds
• What is petroleum?

  A mixture consisting mainly of alkane hydrocarbons
• What are fuels?

  Compounds that release heat energy when burnt
• What is the environmental impact of nitrogen oxides?

  form nitric acid which contributes to acid rain

  photochemical smog which can cause decreased vision and shortness of breath.
• What is fracking, how is it done?

  Fracking is the process of drilling into shale, injecting pressurised water, sand, and chemicals(to fracture the rock) into the ground at high pressure to extract natural gas or oil within the shale rock formations.

  HCl and methanol are the chemicals added to break up shale and prevent corrosion
• What are the 2 types of cracking?

  Catalytic and Thermal