fractional distillation

• crude oil can be separated into different components using fractional distillation
• crude oil is a fossil fuel from deep under the ground. it is a mixture of lots of different compounds
• hydrocarbons contain only hydrogen and carbon
• crude oil is formed naturally from dead plants and animals from millions of years ago
• the high pressures and temperatures under the ground turned the biomass into crude oil. the crude oil soaked into the surrounding rocks which is where it is stored.
• to extract crude oil, we drill into the rock which it is stored, and suck the oil out up to the surfacr
• because crude oil takes so long to form, we call it a finite resource
• Fractional distillation is used to separate crude oil into simpler, more useful mixtures. This method can be used because different hydrocarbons have different boiling points.
• process of fractional distillation

  • heated crude oil enters a tall fractionating column, which is hot at the bottom and gets cooler towards the top
  • vapours from the oil rise through the column
  • vapours condense when they become cool enough
  • liquids are led out of the column at different heights
• hydrocarbons with the longest chains have the highest boiling points so will quickly condense back into a liquid
• bitumen is used for surfacing roads and roofs
• heavy fuel oil fuels for ships and power stations
• the shorter chain hydrocarbons have much lower boiling points so stay in the chamber longer, until they finally reach a cool enough temperature to condense into a liquid
• Small hydrocarbon molecules have weak intermolecular forces
• Long hydrocarbon molecules have stronger intermolecular forces, so they have high boiling points.
• diesel is used for some cars and trains
• keresene fuels aircrafts
• petrol fuels for cars
• liquified petrolium gas is used for domestic cooking and heating
• propane and butane are very short alkanes
• the shorter hydrocarbons are the most flammable, they make the best fuels
• longer hydrocarbons can be broken down into shorter hydrocarbons by cracking
• all substances made from crude oil are called petrochemicals
• what is the main biomass crude oil is made from 


  plankton
• A feedstock is a raw material used to provide reactants for an industrial reaction.
• A petrochemical is a substance made from crude oil, via chemical reactions.
• the shorter hydrocarbons:

  • boiling points below room temperature
  • they are very flammable
  • have a low viscosity
• the longer hydrocarbons :

  • boiling points well above room temperature
  • are very difficult to ignite
  • have a high viscosity
• Complete combustion of a hydrocarbon fuel happens when there is a good supply of air. Carbon and hydrogen atoms in the fuel react with oxygen in an exothermic reaction.
• in complete combustion

  • carbon dioxide and water are produced
  • the maximum amount of energy is given out
• In a Bunsen burner, complete combustion occurs when the air hole is fully open.
• what is the word equation for general complete combustion

  hydrocarbon + oxygen → carbon dioxide + water
• Incomplete combustion happens when the supply of air or oxygen is poor. Water is still produced, but carbon monoxide and carbon are produced. Less energy is released than during complete combustion.
• In a Bunsen burner, incomplete combustion occurs when the air hole is closed.
• many useful materials that modern life depends on are made from the petrochemical industry eg.

  • solvents
  • lubricants
  • polymers
  • detergents
• small hydrocarbon molecules have weak intermolecular forces, so they have low boiling points
• label for small molecules (large molecules is .)

  A) low boiling point

  B) very volatile

  C) flows easily

  D) very flammable

  E) .

  
• mnemonic for the fractions

  Lazy Penguins Keep Drinking Hot Beer

  Liquid Petroleum, Petrol, Kerosene, Diesel, Heavy fuel oil, Bitumen
• in a bunsen burner, complete combustion happens when the air hole is fully open