cracking

• What does viscous mean in terms of flow?

  It means something flows easily
• Why are very viscous substances considered bad fuels?

  They do not flow easily for combustion.
• What does volatile mean?

  How easily something evaporates.
• Why are very volatile substances considered good fuels?

  They evaporate easily, aiding combustion.
• What does flammable mean?

  How easily something burns.
• Why are very flammable substances considered good fuels?

  They catch fire easily, providing energy quickly.
• what is cracking

  breaking long chain hydrocarbons into small chain hydrocarbons using high temperatures
• what type of reaction is cracking

  Thermal decomposition reaction
• what is thermal decomposition

  when you use heat to break something apart
• describe the process of cracking

  1. First, some long chain alkanes are heated until they vaporise into a gas
  2. Then they're passed over a hot, powdered aluminium oxide catalyst 
  3. This breaks the long chain alkanes into a shorter chain alkane and an alkene
• why is cracking of long chain hydrocarbons needed

  1. long chain hydrocarbons are very viscous but not flammable enough to become a good fuel
  2. Theres a high supply of longer chain hydrocarbons but a low demand
  3. Theres a high demand for shorter chain hydrocarbons but the supply is low
• When a long chain alkane is cracked, there aren't enough hydrogen atoms to make two alkanes. Hence, cracking will always produce one alkane and one alkene