fractional distillation

• The boiling points of the liquids in the mixture determine the order in which they vaporize and condense during fractional distillation.
• Fractional distillation separates components based on their boiling points, with higher-boiling compounds condensing first and being collected as fractions from the bottom of the column.
• The column is hot at the bottom and decreases in the temperature towards to top
• short chained column -> gas
• long chain ->high boiling points
• Fractional distillation is used to separate a mixture of long chain hydrocarbons in crude oil into smaller useful fractions
• • complete combustion -> enough oxygen to produce carbon dioxide and water
  • incomplete combustion -> not enough oxygen to fuel to burn , produce carbon monoxide
• short chain hydrocarbons are found at the top of the column because shorter the chain molecules are held together by weak intermolecular forces
• long chain intermolecular forces are held by strong intermolecular
• general formula --> CnH2n+2
• Alkanes are saturated hydrocarbons, meaning they contain only single bonds between carbon atoms.
• Longer the chain, the higher the boiling point of the hydrocarbon
• Four alkanes are: methane, ethane, propane and butane
• Viscosity describes how easily a substance can flow
• Test for Alkanes

  1. Bromine when added to an alkane, will remain brown/orange --> no double bonds
  2. Bromine when added to alkene colourless because of unsaturated hydrocarbons, double bonds will break
• Cracking is an example of thermal decomposition reaction. Long chain turns into short chain
• Cracking involves in the presence of a catalyst and high temperatures (550 degrees Celsius)
• Alkenes are are unsaturated hydrocarbons