hydrocarbons

Cards (12)

  • the homologous series is a family of molecules with the same general formula and similar chemical properties
  • they differ by CH2
  • the bigger the molecule the higher the boiling point
  • examples of homologous series of hydrocarbons are alkanes and alkenes
  • the size of hydrocarbons determine their properties e.g the size of hydrocarbon determines which fraction of crude oil it separates into
  • physical properties are determined by intermolecular forces
  • in small molecule intermolecular forces break more easily as they are much weaker than in big molecules
  • small molecules have lower melting points and boiling points compared to large ones
  • short hydrocarbons ignite easier as they have lower boiling points and are mostly gasses at room temperature. the gas mixes with oxygen to form a gas mixture which burns into flames
  • viscosity: how easily something flows. stronger forces between long hydrocarbons mean it's harder for the liquid to flow so fractions have a higher viscosity
  • they create exothermic reactions as they act as great fuels due to combustion reactions when burnt with oxygen releasing lots of energy
  • complete combustion -all the hydrocarbons are oxidised to form carbon dioxide and water. incomplete combustion-hydrocarbons are burnt on a limited supply of oxygen