mark scheme

• what are the environmental problem caused by particulates?

  global dimming
• Explain why combustion of some fuels causes acid rain

  sulfur in fuel, so it is burnt to produce sulfate dioxide
• explain exothermic reactions in terms of bond making and bond breaking

  energy must be supplied to break bonds. energy is released when bonds are broke. the energy needed to break existing bonds is less than energy released to form bonds
• properties of transition metal copper

  • conducts heat
  • strong
• explain how catalysts increase the rate of reactions

  provides a different pathway for the reaction

  so it lowers the activation energy
• one reason why cobalt (transition metal) can produce different compounds with chlorine

  forms ions with different charges
• describe the bonding in transition metals

  strong electrostatic forces of attraction

  between positive ions and electrons

  outer electrons are delocalised
• why the boiling points of alcohols increase as the number of carbon atoms increase

  intermolecular forces become stronger which requires more energy to break
• properties that make esters suitable for use in perfumes

  • distinctive smell
  • volatile