Alkanes and Alkenes

• What are alkanes and alkenes classified as?

  They are dead useful.
• What elements do alkanes primarily consist of?

  They consist of hydrogen and carbon.
• What type of hydrocarbons are alkanes?

  They are saturated hydrocarbons.
• What defines a homologous series in chemistry?

  • A group of chemicals with similar structures
  • They have similar chemical properties
  • They differ by a constant unit, typically -CH₂
• What do alkanes contain in terms of atoms?

  They contain just carbon and hydrogen atoms.
• What is the general formula for alkanes?

  The formula is $C_nH_{2n+2}$.
• How many hydrogen atoms are in an alkane with 6 carbon atoms?

  There are 14 hydrogen atoms.
• What distinguishes different alkanes from each other?

  They have chains of different lengths.
• What are the first four alkanes?

  1. Methane, $CH_4$
  2. Ethane, $C_2H_6$
  3. Propane, $C_3H_8$
  4. Butane, $C_4H_{10}$
• What do the diagrams of alkanes show about their bonds?

  They show that all atoms have formed bonds.
• How many bonds can carbon atoms form?

  Carbon atoms can form four bonds.
• What type of bond do alkenes have?

  They have a C=C double bond.
• What is a functional group in chemistry?

  • A group of atoms that determine molecular reactivity
  • They define how a molecule behaves in reactions
  • They are consistent within homologous series
• How do alkenes differ from alkanes in terms of hydrogen atoms?

  Alkenes have twice as many hydrogen atoms.
• Why are alkenes known as unsaturated?

  They can make more bonds.
• What happens to the double bond in longer chains of alkenes?

  The double bond can occur at the end or middle.
• What are the first three alkenes?

  1. Ethene, $C_2H_4$
  2. Propene, $C_3H_6$
  3. But-1-ene, $C_4H_8$
• What is the significance of the double bond in alkenes?

  It allows for additional bonding possibilities.
• How do the properties of alkenes change with chain length?

  They can form more bonds with other atoms.
• What are the three alkenes mentioned?

  Ethene, propene, but-1-ene
• What is the structure of ethene?

  C₂H₄ with a double bond
• What is the structure of propene?

  C₃H₆ with a double bond
• What is the structure of but-1-ene?

  C₄H₈ with a double bond
• Where can the double bond in longer chains go?

  At the end or in the middle of the chain
• What can you test for an alkene?

  Using bromine water
• What happens to bromine water when shaken with an alkene?

  It decolorizes from orange to colorless
• Why does bromine water change color with alkenes?

  Due to an addition reaction with bromine
• What do alkanes not react with?

  Bromine water
• What do alkenes react with in combustion reactions?

  Oxygen
• What do alkenes and alkanes produce when burned?

  Carbon dioxide and water
• What is produced during complete combustion of hydrocarbons?

  Carbon dioxide and water
• What is the general equation for complete combustion of hydrocarbons?

  C_xH_y + O₂ → CO₂ + H₂O
• What happens during complete combustion of ethane?

  It forms carbon dioxide and water
• What is the general equation for complete combustion of ethene?

  C₂H₄ + 3O₂ → 2CO₂ + 2H₂O
• What is the general equation for complete combustion of propane?

  C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
• What is the general equation for complete combustion of butane?

  C₄H₁₀ + 6.5O₂ → 4CO₂ + 5H₂O
• What are the differences between alkanes and alkenes?

  • Alkanes: single bonds, saturated
  • Alkenes: double bonds, unsaturated
  • Alkenes react with bromine, alkanes do not
• What are the products of complete combustion of hydrocarbons?

  • Carbon dioxide (CO₂)
  • Water (H₂O)
• What is the significance of the double bond in alkenes?

  • Indicates unsaturation
  • Reacts with bromine in addition reactions
  • Affects physical and chemical properties
• What are the steps in the combustion reaction of hydrocarbons?

  1. Hydrocarbon reacts with oxygen
  2. Produces carbon dioxide and water
  3. Releases energy