Haloalkanes

• Definition of a nucleophile.

  an electron pair donar
• Do haloalkanes undergo nucleophillic addition or substitution.

  substitution
• What is the reaction called when a haloalkane is turned into an alcohol ?


  hydrolysis
• What is the reactant for the hydrolysis of a haloalkane ?

  NaOH
• Write the equation for the hydrolysis of Iodoethane.

  C3H2I + NaOH --> C3H2OH + NaI
• Explain why a carbon-bromine bond is polar.

  Carbon and bromine have different electronegativities.
• How can you compare the rates of hydrolysis of different carbon-halogen bond ?

  -Heat the haloalkane with AgNO3 (aq) in ethanol

  -Halide ions formed which react with AgNO3 and forms a precipitate -Time how long it takes for the precipitate to appear

  -rate=1/time
• Which bond is the fastest to break: C-F , C-Br, C-I ? What does this tell you about the strength of the bonds ?

  Fastest to break = C-I

  Strongest bond = C-F

  Weakest bond = C-I
• What do CFCs contain ?

  Chlorine and fluorine substituents
• What are 3 uses for CFCs ? and why?

  1. Refrigerants = low reactivity 2. Propellants in aerosol sprays = high volatillity and low boilling points 3. Blowing agents in expanding foam = non toxicity
• What do CFCs destroy ?

  the ozone layer
• What does the ozone layer absorb ?

  UV light
• What does the ozone layer do ?

  Protects us from harmful UV radiation which can cause skin cancer.
• What is the equation for the formation of the ozone layer ?

  O2 + O --> O3
• Write an equation for the decomposition of the ozone layer ?

  O3 --> O2 + O
• What is the equation for the ozone layer when equilibrium has been reached ?

  O2 + O <--> O3
• What molecules destroy the ozone layers ? Give two examples.

  free radicals

  Cl radical and NO radical
• What is a free radical ?

  a species with an unpaired electron
• Write the two equations to show how a Cl* (radical) destroys the ozone layer ? Write the overall equation.

  Cl* + O3 --> ClO* + O2

  ClO* + O --> Cl* + O2+

  Overall equation = O3 + O --> 2O2