hydrocarbons

• alkanes = CnH2n+2


  methane CH4

  ethane C2H6

  propane C3H8

  butane C4H10
• methane

  $CH_4$

  A) covalent bond

  
• ethane

  $C_2H_6$

  A) H

  
• propane

  $C_3H_8$

  A) propane

  
• butane

  $C_4H_{10}$

  A) H

  B) C

  
• alkanes are saturated hydrocarbons as they have only single covalent bonds between atoms (no double bonds)
• alkenes = CnH2n


  ethene C2H4

  propene C3H6

  butene C4H8
• alkenes are unsaturated hydrocarbons due to the fact that they contain double bonds also knows as the functional group
• the functional group (the double bond) can be in different place, the number tells you where the functional group is e.g. but-1-ene, the double bond is between the 1st and 2nd carbon and in but-2-ene the double bond is between the 2nd and 3rd carbon
• ethene + bromine -> 1,2-dibromoethene

  this reaction works the same for any alkene or halogen
• bromine water is used to test if it is an alkane or alkene:

  • alkanes DO NOT react with bromine water as bromine atoms bond to the alkene by breaking the double bond
  • alkenes react, turning it from orange to colourless
• the combustion of hydrocarbons releases energy, during combustion the carbon and hydrogen in the fuels are oxidised to produced carbon dioxide and water

  alkane/alkene + oxygen -> carbon dioxide + water