KES

• What is the prefix for a halogen atom fluorine in haloalkanes?

  Fluoro
• What is the prefix for a halogen atom chlorine in haloalkanes?

  Chloro
• What is the prefix for a halogen atom bromine in haloalkanes?

  Bromo
• What is the prefix for a halogen atom iodine in haloalkanes?

  Iodo
• How are haloalkanes named?

  Based on the original alkane with a prefix indicating the halogen atom
• What are the classifications of haloalkanes?

  • Primary Haloalkane: One carbon attached to the carbon adjoining the halogen
  • Secondary Haloalkane: Two carbons attached to the carbon adjoining the halogen
  • Tertiary Haloalkane: Three carbons attached to the carbon adjoining the halogen
• What defines a primary haloalkane?

  One carbon attached to the carbon atom adjoining the halogen
• What defines a secondary haloalkane?

  Two carbons attached to the carbon atom adjoining the halogen
• What defines a tertiary haloalkane?

  Three carbons attached to the carbon atom adjoining the halogen
• What is a nucleophile?

  An electron pair donator
• What happens during a nucleophilic substitution reaction?

  A halogen atom is swapped for another atom or group of atoms
• Why does the carbon atom in haloalkanes have a small positive charge?

  Due to the electronegativity difference between carbon and the halogen
• What affects the rate of nucleophilic substitution reactions?

  The strength of the C-X bond
• Which C-X bond is the weakest?

  1. I
• Which C-X bond is the strongest?

  1. F
• Which type of haloalkane is the fastest to substitute?

  Iodoalkanes
• Which type of haloalkane is the slowest to substitute?

  Fluoroalkanes
• What is the mechanism of nucleophilic substitution reactions?

  • Nucleophiles have a lone pair and act as electron pair donors
  • Curly arrows show the movement of two electrons
  • Curly arrows start from a lone pair or the center of a bond
• What reagent is used in nucleophilic substitution with aqueous hydroxide ions?

  Potassium (or sodium) hydroxide
• What is the change in functional group when a halogenoalkane reacts with aqueous hydroxide ions?

  Halogenoalkane to alcohol
• What conditions are required for nucleophilic substitution with aqueous hydroxide ions?

  Aqueous solution and heat under reflux
• What is hydrolysis in the context of haloalkanes?

  The splitting of a haloalkane by a reaction with water
• What is the role of aqueous silver nitrate in comparing the rate of hydrolysis reactions?

  It forms a silver halide precipitate with the halide leaving group
• What color precipitate does AgI form?

  Yellow precipitate
• What color precipitate does AgBr form?

  Cream precipitate
• What color precipitate does AgCl form?

  White precipitate
• What is the relationship between the strength of the C-X bond and the rate of substitution reactions?

  The weaker the bond, the easier it is to break and the faster the reaction
• What are the uses and concerns regarding CFCs?

  • Developed for aerosols, refrigerants, and air-conditioning
  • Low reactivity, volatility, and non-toxicity
  • Concerns due to toxicity and effect on the ozone layer
• What are HFCs and why are they used instead of CFCs?

  • Hydrofluorocarbons (e.g., CH2FCF3)
  • Used for refrigerators and air-conditioners
  • Safer as they do not contain the C-Cl bond
• What is the role of CO2 in relation to CFCs?

  • Used as a blowing agent for producing expanded polymers
  • Alternative to CFCs
• What is the function of the ozone layer?

  • Filters out harmful UV radiation from the sun
  • Beneficial for life on Earth
• What is the effect of ozone in the lower atmosphere?

  It is a pollutant and contributes to smog formation
• How is ozone formed in the atmosphere?

  1. UV light splits O2 into free radicals
  2. Free radicals react with O2 to form O3
• How is ozone depleted in the atmosphere?

  1. Ozone absorbs UV light and breaks down into O2 and O
  2. Continuous cycle of formation and depletion
• What is the relationship between the rate of ozone formation and removal?

  They are equal, maintaining a constant amount of ozone
• What are the biological effects of UV light?

  Increases risk of skin cancer and crop mutation
• How do radicals from CFCs and NOx affect ozone?

  • Catalyze the breakdown of ozone
  • Contribute to ozone layer depletion
• How do chlorine radicals contribute to ozone depletion?

  • Formed from CFCs by UV radiation
  • Catalyze the decomposition of ozone
  • Regenerated, allowing one Cl radical to destroy many ozone molecules
• What is the overall equation for the destruction of ozone by chlorine radicals?

  O3 + O → 2 O2
• What legislation has been taken regarding CFCs?

  • Ban on the use of CFCs
  • Supported by chemists
  • Development of alternative chlorine-free compounds