organic chemistry

• What is organic chemistry primarily concerned with?

  Compounds that contain carbon
• What are hydrocarbons?

  Compounds formed from carbon and hydrogen atoms only
• What is the general formula for alkanes?

  C_nH_2n+2
• What characterizes alkanes in terms of bonding?

  They have all C—C single bonds
• What are the first four alkanes?

  • Methane: CH₄
  • Ethane: C₂H₆
  • Propane: C₃H₈
  • Butane: C₄H₁₀
• How do the properties of hydrocarbons change with the length of the carbon chain?

  Shorter chains are less viscous, more volatile, and more flammable
• Why are short-chain hydrocarbons used as bottled gases?

  They have lower boiling points and are stored under pressure as liquids
• What is produced during the complete combustion of hydrocarbons?

  Carbon dioxide and water vapour
• What is the balanced equation for the complete combustion of methane (CH₄)?

  CH₄ + 2O₂ → CO₂ + 2H₂O
• Why is cracking used in the processing of crude oil?

  To convert long-chain hydrocarbons into shorter, more useful ones
• What is the process of fractional distillation used for?

  • To separate different hydrocarbons in crude oil
  • Based on boiling points
  • Produces fractions with similar carbon atom numbers
• What is crude oil primarily formed from?

  The remains of plants and animals, mainly plankton
• Why are fossil fuels considered non-renewable resources?

  They take millions of years to form and are being used faster than they are created
• What is the temperature gradient in a fractionating column?

  Hot at the bottom and cooler at the top
• What happens to longer hydrocarbons in a fractionating column?

  They condense back into liquids and drain out early
• What are some products derived from crude oil?

  Diesel oil, kerosene, heavy fuel oil, and LPG
• What is the significance of alkenes in organic chemistry?

  They are more reactive than alkanes and used to make other compounds
• How can bromine water be used to test for alkenes?

  It decolourises when added to an alkene
• What is catalytic cracking?

  A process where long-chain hydrocarbons are split using a catalyst
• What is the balanced equation for the cracking of pentane (C₅H₁₂) into ethene and another hydrocarbon?

  C₅H₁₂ → C₂H₄ + C₃H₈
• What are the different methods of cracking hydrocarbons?

  • Catalytic cracking: uses a catalyst
  • Steam cracking: mixes with steam and heats to high temperatures
  • Thermal decomposition: breaking down by heating