Hydrocarbons

• Alkane general formula?

  CnH2n+2
• As length of chain of alkane increase:

  • boiling point increases
  • less volatile
  • more viscous
  • less flamable
• Combustion of alkane:

  hydrocarbon + oxygen -> carbon dioxide + water
• Fractional distillation alkane used for:

  1. Petrol - fuel
  2. Kerosene fuel for jet engines
  3. Diesel - fuel
  4. Heavy fuel oil - fuel oil , lubricating oil
  5. Bitumen - roads and roofs
• A feedstock is a raw material used to provide reactants for an industrial reaction.
• A petrochemical is a substance made from crude oil, via chemical reactions.
• crude oil - a mixture of hydrocarbons that is formed from the remains of ancient plants and animals (plankton)
• Cracking is a process of thermal decomposition
• steam cracking

  1. vaporise
  2. Combine with steam
  3. heat
• Catalytic cracking:

  1. vaporise
  2. Let steam pass through hot powdered aluminium oxide
• alkenes have a double bond
• Additional reactions of alkenes:

  • hydrogen - req catalyst. produces alkane
  • water - req high temps and catalyst. produces alcohol
  • halogens - decolourises bromine water. produces halogenoalkanes
• Additional polymerisation

  A) Ethene

  B) polyethene

  
• Alcohol - alkanes that have an OH functional group
• General formula of alcohols?

  CnH2n+1OH
• uses of alcohol?

  • fuels
  • Solvents
• Reactions of alkenes:

  A) Ethene

  B) Bromine

  C) Dibromoethane

  
• Alkene + hydrogen → alkane

  it is called hydrogenation, and it needs a catalyst
• Alkene + water (steam) → alcohol

  This is called hydration, and it needs a temperature of 300°C and a catalyst.
• Alkene + halogen → halogenoalkane. EG:

  A) Ethene

  B) Chlorine

  C) Dichloroethane

  
• Combustion of alcohol:

  ethanol + oxygen → carbon dioxide + water
• Carboxylic acid general formula:

  CnH2n+1COOH
• Hydrogenation

  • Temperatures of approximately 150 oC and a nickel catalyst are required