Cracking crude oil and alkenes

• What is crude oil primarily composed of?

  A mixture of hydrocarbons
• What process is used to separate hydrocarbons in crude oil?

  Fractional distillation
• Why are shorter hydrocarbons considered better fuels?

  They are more flammable
• What happens to longer chain hydrocarbons during cracking?

  They are broken down into shorter hydrocarbons
• What type of reaction is cracking?

  Thermal decomposition reaction
• What does "thermal" refer to in thermal decomposition?

  Heating
• What does "decomposition" mean in thermal decomposition?

  Breaking down molecules
• What are the two methods of cracking?

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

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

  Hot powdered aluminium oxide
• What happens to long hydrocarbons in catalytic cracking?

  They split into smaller hydrocarbons
• What is mixed with hydrocarbons in steam cracking?

  Steam
• What is produced when long chain alkanes are cracked?

  A shorter alkane and an alkene
• What is the formula for decane?

  C₁₀H₂₂
• What is the balanced equation for cracking decane into ethene?

  C₁₀H₂₂ → C₈H₁₈ + C₂H₄
• What is a homologous series?

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

  Alkenes have a double bond
• Why are alkenes more reactive than alkanes?

  They have a double bond
• What happens when bromine water is added to alkenes?

  It decolorizes from orange to colorless
• What can alkenes be used to produce?

  Polymers and other chemicals
• What are the key features of alkenes compared to alkanes?

  • Alkenes have a double bond; alkanes have single bonds.
  • Alkenes are unsaturated; alkanes are saturated.
  • Alkenes are more reactive than alkanes.
• What is the process of cracking hydrocarbons?

  1. Heat and vaporize long chain hydrocarbons.
  2. For catalytic cracking, pass vapor over a catalyst.
  3. For steam cracking, mix vapor with steam and heat.
  4. Produce shorter hydrocarbons and alkenes.
• What are the differences between catalytic cracking and steam cracking?

  • Catalytic cracking uses a catalyst (aluminium oxide).
  • Steam cracking uses steam and high temperatures.
  • Both processes produce shorter hydrocarbons from long chains.