rate and extent of chemical change

• What test is used to identify oxygen? (1 mark)

  • Glowing splint relights
• What test is used to identify hydrogen? (1 mark)

  • Lit splint ignites with a squeaky pop
• What test is used to identify Carbon dioxide? (1 mark)

  • If its bubbled through limewater, it turns cloudy.
• What test is used to identify chlorine? (1 mark)

  • Bleaches litmus paper.
• What is meant by the term ‘equilibrium’? (2 marks)

  • A state in a reaction where the rate of the forwards reaction is equal to the backwards reaction
  • In a closed system.
• Explain how a catalyst increases the rate of reaction (2 marks)

  • It provides an alternate pathway for the reaction
  • With a lower activation energy
• Suggest why a catalyst is used (do not refer to increasing rate of reaction) (1 mark)

  • Less energy is needed
• Which catalyst is used when ammonia is produced from nitrogen and hydrogen? (1 mark)

  • Iron
• Explain the effect of increasing temperature on the rate of reaction (3 marks)

  • More kinetic energy
  • So more frequent successful collisions between particles
  • So the rate of reaction increases
• Explain the effect of increasing concentration of a reaction (3 marks)

  • More particles in a given volume
  • So more frequent successful collisions
  • So speeding up reaction