C7

• What is crude oil?

  A mixture of compounds from ancient biomass
• Why is crude oil considered a finite resource?

  It cannot be replaced as it is used up
• What is a hydrocarbon?

  A compound of hydrogen and carbon atoms
• What are alkanes?

  Saturated hydrocarbons with formula CnH2n+2
• What defines a homologous series?

  Compounds with same formula and properties
• Describe the combustion of hydrocarbons.

  • Exothermic reaction with oxygen
  • Complete combustion: produces CO2 and water
  • Incomplete combustion: produces carbon or CO and water
• Describe the physical properties of alkanes.

  • First few are gases, then liquids, then solids
  • Boiling points and viscosity increase with size
  • Volatility and flammability decrease with size
  • Generally poor reactivity
• Explain how fractional distillation of crude oil takes place.

  • Crude oil is heated and vaporized
  • Vapor rises in a fractionating column
  • Column is hotter at the bottom, cooler at the top
  • Hydrocarbons condense at different heights
  • Large molecules collected at the bottom
  • Small molecules collected at the top
• What is cracking?

  Thermal breakdown of large hydrocarbons
• What type of reaction is cracking?

  Thermal decomposition
• What are the conditions for cracking?

  Heated vapor over a catalyst or steam
• How are the products of cracking used?

  • Alkanes and alkenes produced
  • Used as polymers
  • Starting materials for synthesis
• What is an alkene?

  Unsaturated hydrocarbon with a C=C bond
• What is the test for alkenes?

  Add bromine water; color changes
• Describe the combustion of alkenes.

  • Burns with smoky flames
  • Due to incomplete combustion