5. kinetics

• What must happen for a reaction to occur?

  Particles must collide
• How is the rate of reaction defined?

  Change in concentration per unit time
• What is the formula for rate of reaction?

  Rate = amount of reactant used / time
• Why do most collisions not lead to a reaction?

  Particles often bounce off each other
• What is required for a reaction to occur during a collision?

  Correct orientation and sufficient energy
• What is activation energy?

  Minimum energy required for a reaction
• What does an energy profile diagram show?

  Energy changes during a reaction
• What happens to bonds during a reaction?

  Bonds stretch and break as energy increases
• How is activation energy represented in an energy profile diagram?

  As the difference between reactants and peak energy
• What does a low activation energy indicate?

  Less energy is needed for a reaction
• What does the Maxwell-Boltzmann distribution illustrate?

  Energy distribution of gas particles
• What does the peak of the Maxwell-Boltzmann curve represent?

  The most likely energy of particles
• How does temperature affect the rate of reaction?

  Higher temperature increases kinetic energy
• What happens to the area beyond activation energy at higher temperatures?

  It increases due to more energetic particles
• What occurs when temperature is decreased?

  Fewer particles exceed activation energy
• Why do reactions occur faster at higher temperatures?

  More frequent and energetic collisions happen
• How does concentration affect the rate of reaction?

  Higher concentration increases collision frequency
• What is the role of a catalyst in a reaction?

  It lowers activation energy and speeds up reactions
• What is zeolite?

  A catalyst with a honeycomb structure
• How does a catalyst affect the Maxwell-Boltzmann distribution?

  It shifts activation energy to the left
• What is a common method to measure reaction rates?

  Timing precipitate formation
• What is the disappearing cross reaction?

  A method to time precipitate formation
• What is a limitation of the disappearing cross method?

  Difficulty in determining when the cross disappears
• How can mass loss be measured in reactions?

  By using a top pan balance
• What is a gas syringe used for in experiments?

  To measure the volume of gas produced
• What should be done if toxic gas is produced?

  Use a fume cupboard for safety
• What are the key factors affecting the rate of reaction?

  • Temperature
  • Concentration
  • Pressure
  • Catalysts
• How does increasing temperature affect reaction rates?

  • Increases kinetic energy of particles
  • Leads to more frequent collisions
  • Results in more energetic collisions
• How does increasing concentration affect reaction rates?

  • More particles in the same volume
  • Increases frequency of collisions
  • Higher chance of reactions occurring
• How do catalysts work in chemical reactions?

  • Provide an alternative pathway
  • Lower activation energy
  • Remain unchanged after the reaction
• What are the methods to measure reaction rates?

  • Timing precipitate formation
  • Measuring mass loss
  • Measuring gas volume produced
• What is the significance of the area under the Maxwell-Boltzmann curve?

  • Represents total number of molecules
• What is the difference between mode and mean energy in a Maxwell-Boltzmann distribution?

  • Mode: Most likely energy of particles
  • Mean: Average energy of particles
• What happens to the activation energy when a catalyst is used?

  • Activation energy decreases
  • More particles can react