Fractional disilation

• How is crude oil formed?

  • Formed millions of years ago
  • By the breakdown of plant and animal remains
  • At high pressures and temperatures
• What is crude oil made up of?

  Alkanes (branched and straight chained)
• What is Fractional distillation used for?

  Breaks down crude oil into useful products
• Describe the process of fractional distillation

  • Heat crude oil in a furnace
  • The shorter chain hydrocarbons condense in the trays nearer to the top of the tower where its cooler and they have lower boiling points
  • Longer chain hydrocarbons cool and condense at the bottom
• Shorter chain alkanes demand is higher than the supply as they are more useful e.g fuel
• Longer chain alkanes demand is lower than the supply
• What bonds are broken with fractional distillation?

  Van Der Waals forces between molecules
• State the meaning of saturated?

  No double bonds between carbon atoms
• Describe the features of fractional distillation (4 marks)

  • Boling point depends on the size of the alkane
  • Smaller alkanes cool + condense at the top and larger alkanes cool and condense at the bottom
  • It has a negative temperature gradient
  • Fractions have different boiling points
• What is a negative temperature gradient?

  The fractionating column is hotter at the bottom and cooler at the top
• What is a fraction?

  A mixture of hydrocarbons with similar boiling points