Cracking Crude Oil and alkenes

• What is crude oil primarily composed of?

  A mixture of different hydrocarbons
• What process is used to separate hydrocarbons in crude oil by the length of their carbon chains?

  Fractional distillation
• Why are shorter hydrocarbons considered better fuels?

  They are more flammable
• What is the purpose of cracking in the context of hydrocarbons?

  To break down longer hydrocarbons into shorter, more flammable ones
• What type of reaction is cracking classified as?

  A thermal decomposition reaction
• What does the term "thermal" refer to in thermal decomposition?

  Heating
• What does "decomposition" mean in the context of thermal decomposition?


  Breaking down molecules
• What are the two methods of cracking that need to be known?

  Catalytic cracking and steam cracking
• What is the first step in both catalytic and steam cracking?

  To heat and vaporize long chain hydrocarbons
• What catalyst is used in catalytic cracking?

  Hot powdered aluminium oxide
• In catalytic cracking, what happens when hydrocarbon vapor comes into contact with the catalyst?

  It splits apart into two smaller hydrocarbons
• What is the process used in steam cracking after vaporizing hydrocarbons?

  Mixing them with steam and heating to a high temperature
• What is the general equation for the cracking of long chain alkanes?

  Long chain alkane → shorter alkane + alkene
• If decane is cracked, what are the products formed?

  A shorter alkane and an alkene
• How do you determine the number of carbons and hydrogens in the products of cracking?

  By subtracting the number of carbons and hydrogens in the known product from the reactant
• What is the formula for the unknown alkane when decane is cracked into ethene?

  C$_8H_{18}$
• What is a homologous series?

  A group of similar compounds with similar properties
• What is the key structural difference between alkenes and alkanes?

  Alkenes have a double bond, while alkanes have only single bonds
• Why are alkenes considered more reactive than alkanes?

  Because they have a double bond
• What happens when bromine water is added to a solution of alkenes?

  It decolorizes from orange to colorless
• What is the significance of the reaction of alkenes with bromine water?


  It is a test for alkenes
• How can alkenes be used in the production of polymers?

  Because their double bonds can break to form two more bonds
• What are the key features of alkenes compared to alkanes?

  • Alkenes are unsaturated (contain double bonds)
  • Alkanes are saturated (contain only single bonds)
  • Alkenes are more reactive than alkanes
  • Alkenes can react with bromine water to decolorize it
  • Alkenes can be used to produce polymers