4.2.2 - Haloalkanes

• What is bond enthalpy?

  The energy required to break one mole of gaseous bonds
• How does the bond enthalpy of carbon halogen bonds change in haloalkanes?

  It decreases from C-F to C-I
• What does CFC stand for?

  Chlorofluorocarbon
• What are CFCs used for?

  As refrigerants and aerosol propellants
• How are CFCs broken down in the atmosphere?

  By UV light forming chlorine radicals
• What role do chlorine radicals play in the atmosphere?

  They catalyse the breakdown of ozone
• What is a haloalkane?

  An organic compound with a halogen atom
• What is hydrolysis?

  The breakdown of a compound by water
• How can the rate of haloalkane hydrolysis be determined?

  By reacting with water in the presence of AgNO3 and ethanol
• What is a nucleophile?

  An electron pair donor
• What occurs during nucleophilic substitution?

  An electron pair donor attacks an electrophilic atom
• What is the molecular formula of ozone?

  O3
• What is the function of ozone in the atmosphere?

  It absorbs UV light
• What can catalyse the breakdown of ozone?

  Chlorine radicals and other radicals like •NO
• What is a radical?

  A species with an unpaired electron
• What is substitution in chemistry?

  A reaction where one atom/group replaces another
• How do haloalkanes undergo substitution reactions?

  With aqueous alkali or with water
• How does the rate of substitution reaction change in haloalkanes?

  It increases from C-F to C-I
• Why does the rate of substitution reaction increase from C-F to C-I?

  Due to decreasing bond enthalpy of carbon-halogen bond