Crude oil, fuels and carbon compounds

• How crude oil was formed:

  1. Microscopic plants and animals die and fall to the sea bed.
  2. Layers of sand and mud fall on top.
  3. Pressure and high tempereature cause oil to form.
  4. Oil is obtained by drilling.
• Crude oil is a mixture of hydrocarbons.
• A hydrocarbon is a molecule that contains only carbon and hydrogen.
• Process of fractional distillation:

  • Crude oil is heated until it vaporizes.
  • The gaseous crude oil enters the bottom of the fractional distillation column, where it is hottest.
  • Hydrocarbons with boiling points higher than the temperature at their level condense into liquids and are removed.
  • Hydrocarbons with lower boiling points remain as gases and rise to cooler levels until they condense.
• In a fractional distillation column:

  • the lowest temperature is at the top
  • the highest temperature is at the bottom
• Hydrocarbons with the lowest boiling points rise to the top of the column and have short carbon chains.
• Fire needs oxygen, heat and fuel.
• Combustion is the scientific name for burning.
• Combustion of hydrocarbons produces carbon dioxide and water.
• Benefits of using hydrogen as a fuel:

  • renewable as it is made from electrolysis of water
  • doesn't release CO2
• Downsides of using hydrogen as a fuel:

  • large amounts of electricity are needed for electrolysis
  • bulky and heavy storage containers
  • it is flammable and explosive
• Prefixes for alkanes and alkenes:

  • meth- 1 carbon
  • eth- 2 carbons
  • prop- 3 carbons
  • but- 4 carbons
  • pent- 5 carbons
• The general formula for alkanes:

  $C_nH_{2n\ +\ 2}$
• Alkenes contain a C=C double bond.
• The general formula for alkenes:

  $C_nH_{2n}$
• To test for alkanes and alkenes, add bromine.
• When bromine is added to an alkane, it remains orange as there are no available bonds for it to attatch.
• When bromine is added to an alkene, it becomes colourless as the double bond can be broken, leaking available bonds for it to attach.
• Alkanes:

  • C-C single bonds
  • saturated
  • unreactive
• Alkenes:

  • C=C double bonds
  • unsaturated
  • reactive
• Process of cracking:

  • Large hydrocarbons are broken into smaller molecules using heat as a catalyst.
  • These molecules are then seperated by distillation.
• Alkenes are a byproduct of cracking.
• A polymer is a compound of a long chain molecule made from smaller molecules called monomers.
• Addition polymers are made from one type of monomer.
• Condensation polymers are made of two or more different monomers.
• Polymerisation requires heat and pressure.
• An isomer is a molecule with the same molecular formula as another molecule, but has a different chemical structure.
• Isomers contain the same number of atoms of each element, but have different arrangements of their atoms.
• But-1-ene has a methyl group on the first carbon atom.
• But-2-ene has a methyl group on it's second carbon atom.