Hydro carbons

• What elements do hydrocarbons contain?


  Hydrogen and carbon atoms
• What is the general formula for alkanes?


  CₙH₂ₙ₊₂
• What are the first four alkanes?


  Methane, ethane, propane, butane
• What is the molecular formula for methane?


  CH₄
• What is the molecular formula for ethane?


  C₂H₆
• What is the molecular formula for propane?


  C₃H₈
• What is the molecular formula for butane?


  C₄H₁₀
• How do hydrocarbon properties change with carbon chain length?


  • Shorter chains are more volatile and less viscous
  • Shorter chains have lower boiling points
  • Shorter chains are more flammable
  • Short-chain hydrocarbons are used as bottled gases
• What occurs during complete combustion of hydrocarbons?


  It releases energy, carbon dioxide, and water vapor
• What is the general equation for the complete combustion of a hydrocarbon?


  hydrocarbon + oxygen → carbon dioxide + water (+ energy)
• What happens to carbon and hydrogen during combustion?


  Both are oxidized
• Write the balanced equation for the complete combustion of methane (CH₄).


  CH₄ + 2O₂ → CO₂ + 2H₂O
• How many oxygen molecules are needed to balance the combustion of methane?


  Two oxygen molecules
• Write a balanced symbol equation for the complete combustion of ethane (C₂H₆).


  C₂H₆ + 7/2 O₂ → 2CO₂ + 3H₂O
• Compare the properties of alkanes in terms of viscosity, boiling point, and flammability.


  • Viscosity: Shorter chains are less viscous
  • Boiling Point: Shorter chains have lower boiling points
  • Flammability: Shorter chains are more flammable