Hydrocarbons

• A hydrocarbon contains hydrogen and carbon ONLY.
• What is a functional group?

  An atom or group of atoms that give a compound its chemical properties.
• What is a Homologous group?

  A group of organic compounds with the same functional group.
• What is the general formula for an alkane?


  CnH2n+2
• What type of bonds are present in alkanes?


  Single covalent
• What are the first four alkanes?

  Methane, Ethane, Propane, Butane
• Where do hydrocarbons come form?

  Crude oil.
• What is fractional distillation?

  Separating hydrocarbons according to their boiling points.
• What is a fraction?

  A group of compounds that have a similar boiling or number of carbons.
• Explain how fractional distillation separates crude oil.

  1. Mixture is heated gently
  2. Substance with the lowest boiling point vapourises first
  3. Substance travels through a condenser and is condensed and collected
  4. As the temperature rises, the next substance vapourises
• As the number of carbons increase, the boiling point increases.
• As the number of carbons increase, the flammability decreases.
• As the number of carbons increase, the cleanliness of the flame decreases.
• As the number of carbons increase, the viscosity increases.
• Why are small hydrocarbon molecules better fuels?

  They are more flammable, burn a cleaner flame and release more energy at a quicker rate.
• What is the general formula for an alkene?


  CnH2n
• An alkene added to bromine water will turn go colourless.
• Alkenes have one double carbon bond.
• What is cracking?

  A process in which long chain hydrocarbons can be broken down to produce smaller more useful molecules. This process involves heating the hydrocarbons to vaporise them. The vapours are passed over a hot catalyst. The products of cracking include shorter chain alkenes and alkanes.
• Alkene + halogen --> halogenoalkane
• Alkene + hydrogen --> alkane
• Alkene + steam --> alcohol
• What are the first four alkenes?

  Methane, ethene, propene, butene
• Combustion makes carbon dioxide and water.
• Esters are made when an alcohol and carboxylic acid join together.
• What is ethylmethanoate made from?

  Ethanol and methanoic acid
• What are the first four carboxylic acids?

  Methanoic acid, ethanoic acid, propanoic acid, butanoic acid
• What are the first four alcohols?

  Methanol, ethanol, propanol, butanol
• What is methylpropanoate made from?

  Methanol and propanoic acid
• What is ethylethanoate made from?

  Ethanol and ethanoic acid