Haloalkanes

• What do C-X bonds refer to in chemistry?

  1. X bonds refer to carbon-halogen bonds.
• How is the strength of C-X bonds measured?

  It is measured by their bond enthalpy.
• What does a larger bond enthalpy indicate about a C-X bond?

  A larger bond enthalpy indicates a stronger C-X bond.
• Which carbon-halogen bond is the strongest?

  The C-F bond is the strongest.
• Which carbon-halogen bond is the weakest?

  The C-I bond is the weakest.
• How are bond enthalpies of haloalkanes measured?

  They are measured by the rate of reaction of the haloalkane with water and AgNO₃.
• What type of reaction is the hydrolysis of haloalkanes?

  It is an example of a hydrolysis reaction.
• What is hydrolysis in the context of haloalkanes?

  • The addition of water to break a bond.
  • Involves AgNO₃ and H₂O (with ethanol) to measure bond enthalpy.
• Write the equation for the hydrolysis of HCl with water.

  H₃C-Cl + H₂O → H₃C-OH + HCl
• What is the significance of the precipitate formed in the hydrolysis reaction?

  The color of the precipitate can help identify the haloalkane.
• How does the rate of formation of the precipitate relate to the strength of the C-X bond?

  The faster the rate of formation of the precipitate, the weaker the C-X bond.
• What are the reactants and products of the reaction between haloalkane and NaOH?

  • Reactants: Haloalkane and NaOH(aq)
  • Products: Alcohol and NaCl
• What type of reaction occurs when a haloalkane reacts with NaOH?

  It is a nucleophilic substitution reaction.
• What are some examples of haloalkanes?

  • CH₃Cl (methyl chloride)
  • C₂H₅Cl (ethyl chloride)
  • C₃H₇Cl (propyl chloride)
• What environmental concerns are associated with organohalogen compounds?

  CFCs are a danger to the environment due to chlorine free radicals they can form.
• How do chlorine free radicals affect the ozone layer?

  They can degrade the ozone layer.
• What is the equilibrium involving the ozone layer?

  • O₂ + UV light → 2O
  • O + O₃ → 2O₂
• What happens when a CFC reaches the upper atmosphere?

  It can disrupt the equilibrium of the ozone layer.
• What is photodissociation?

  Photodissociation is the breaking of a bond by UV light.
• What are the steps that occur after the formation of a chlorine radical from a CFC?

  1. Formation of chlorine radical via homolytic fission.
  2. Propagation steps involving reactions with ozone.
  3. Overall reaction leading to ozone depletion.
• What international legislation limits the use of CFCs?

  The Montreal Protocol limits the use of CFCs in industry.
• What are suitable alternatives to CFCs?

  Short chain alkanes or chlorine-free haloalkanes are suitable alternatives.
• What can form NO free radicals?

  Air travel traffic and lightning storms can form NO free radicals.
• What is the effect of NO free radicals on the ozone layer?

  They can have similar effects on the ozone layer as chlorine free radicals.
• What is the general reaction format for free radical formation?

  • A + B → C + D
  • Involves the breaking of bonds to form radicals.
• What is the equation for the formation of NO from nitrogen and oxygen?

  NO + O₂ → NO₂ + O
• What is the equation for the reaction of ozone with oxygen?

  O₃ + O → 2O₂