fractional distillation

• What type of resource is crude oil?

  Non-renewable (finite) resource
• How is crude oil formed?

  From fossilised remains of ancient plankton
• Where is crude oil found?

  In rocks
• What is crude oil used to produce?

  Fuels and other important chemicals
• What is crude oil a mixture of?

  Different compounds not chemically combined
• What are most compounds in crude oil?

  Hydrocarbons
• What are hydrocarbons made of?

  Only hydrogen and carbon atoms
• How do hydrocarbons differ?

  In their size, affecting their properties
• What is fractional distillation?

  • Process of separating crude oil
  • Groups hydrocarbons by similar carbon atom numbers
  • These groups are called "fractions"
• What are long-chain hydrocarbons?

  Hydrocarbons with lots of carbon atoms
• What are short-chain hydrocarbons?

  Hydrocarbons with few carbon atoms
• What formula do fractions largely follow?

  CnH2n+2 for alkanes
• What are the steps of fractional distillation?

  1. Crude oil is heated until it evaporates
  2. Vapour enters a fractionating column
  3. Long-chain hydrocarbons condense at the bottom
  4. Short-chain hydrocarbons rise and condense higher
  5. Fractions are collected for processing
• What happens to crude oil in the fractionating column?

  It evaporates and rises upwards
• Where is the temperature highest in the fractionating column?

  At the bottom of the column
• What happens to long-chain hydrocarbons in the column?

  They condense at the bottom as liquids
• What happens to short-chain hydrocarbons in the column?

  They pass up and condense at lower temperatures
• What are the end products of the fractions collected?

  • Fuels (e.g. petrol, diesel)
  • Feedstock for petrochemical industry
  • Used to make solvents, lubricants, detergents