Alkanes: properties & combustion

• What are alkanes classified as?

  A homologous series of hydrocarbons
• What do alkanes contain?

  Only carbon and hydrogen atoms
• What is a key characteristic of alkanes?

  They have no double bonds
• How many alkanes were covered in the video?

  The first four alkanes
• What happens to the boiling point of alkanes as the carbon chain length increases?

  The boiling point increases with chain length
• What state do the first four alkanes exist in at room temperature?

  Gases
• What happens to longer alkanes at room temperature?

  They are liquids or solids
• Why are shorter alkanes more volatile?

  They have lower boiling points
• What does it mean for longer alkanes to be more viscous?

  They are thick and sticky
• How does flammability change with alkane chain length?

  Shorter alkanes are more flammable
• What is one main use of hydrocarbons like alkanes?

  They are used as fuel
• What is produced during complete combustion of hydrocarbons?

  Carbon dioxide and water
• What type of reaction is combustion?

  An exothermic reaction
• What happens to hydrogen and carbon during combustion?

  They are oxidized
• What is the molecular formula for propane?

  C3H8
• How many oxygen molecules are needed for the complete combustion of propane?

  5O2 molecules
• What is the molecular formula for nonane?

  C9H20
• How many oxygen molecules are needed for the complete combustion of nonane?

  14O2 molecules
• What are the properties of alkanes based on carbon chain length?

  • Boiling point increases with chain length
  • Shorter alkanes are gases at room temperature
  • Longer alkanes are liquids or solids
  • Shorter alkanes are more volatile
  • Longer alkanes are more viscous
  • Shorter alkanes are more flammable
• What is the process of combustion in hydrocarbons?

  • Hydrocarbon reacts with oxygen
  • Produces carbon dioxide and water
  • Releases energy (exothermic reaction)
  • Requires sufficient oxygen for complete combustion
• What is the key takeaway about alkanes and their properties?

  • Properties depend on carbon chain length
  • Shortest alkanes are most volatile and flammable
  • Combustion produces CO2 and H2O