7.1.3 Collision Theory and Activation Energy

• What does the transition state represent in a chemical reaction?

  The highest energy point during the reaction
• What are the factors that affect activation energy?

  Concentration, temperature, and catalyst
• How does heating reactants influence reaction rates?

  It increases collision frequency, lowering activation energy
• What is the definition of collision theory?

  It explains how chemical reactions occur.
• What happens at the transition state?

  Reactants break apart and products form
• What is the name of the energy shown in the graph?

  Activation energy
• How does concentration affect activation energy?

  • Higher concentration decreases activation energy
  • Example: Shaking vinegar and baking soda more strongly
• What are the key features of the activation energy graph?

  • Activation energy is the energy required to reach the transition state
  • Transition state is the highest energy point on the reaction pathway
  • Enthalpy change (ΔH) is negative, indicating an exothermic reaction
  • Reactants have higher energy than products
• What does the peak in the graph represent?

  The transition state
• What role do catalysts play in activation energy?

  • Catalysts lower activation energy
  • Example: Adding enzymes to biological reactions
• What does the peak in the energy profile diagram indicate?

  It indicates the transition state of the reaction
• Why do factors that affect activation energy influence reaction rates?

  They reduce energy needed to start reactions
• In an endothermic reaction (diagram B), how does the energy of the reactants compare to the energy of the products?

  Reactants have lower energy
• What two conditions must be met for successful collisions to form products?

  Correct orientation and enough energy.
• What happens to activation energy when temperature increases?

  It decreases
• What does $E_a$ represent in the context of a reaction coordinate diagram?


  Activation energy
• Why does reaction A proceed at a slower rate than reaction B?

  Fewer particles have sufficient energy to react.
• What role does orientation play in the success of a collision according to collision theory?

  Correct orientation allows effective interaction.
• In a reaction coordinate diagram, what does the purple line represent?

  Reaction coordinate
• How does shaking a mixture of vinegar and baking soda affect the reaction rate?

  • Increases collision frequency
  • Leads to more successful reactions
  • Makes the reaction occur faster
• What must happen for a chemical reaction to occur according to collision theory?

  Reaction particles need to collide.
• What is collision frequency in chemical reactions?

  Number of particle collisions per second
• What is the relationship between activation energy and reaction rate?

  It is inverse.
• What is the effect of temperature on activation energy?

  • Higher temperature decreases activation energy
  • Example: Heating reactants to speed up collision frequency
• What is the difference between reaction coordinate diagrams A and B?

  • Diagram A: Represents an exothermic reaction.
  • Diagram B: Represents an endothermic reaction.
• How is activation energy illustrated in an energy profile diagram?

  • Shown by a red arrow
  • Indicates the energy required to reach the transition state
  • The peak represents the transition state before products form
• What can be inferred from the activation energy profiles of reactions A and B?

  • Profile A has higher activation energy (E_a)
  • Reaction A proceeds slower than reaction B
  • Fewer particles can reach the transition state in A
• What happens to the reaction rate when the collision frequency is high?

  The reaction rate increases significantly
• What happens to activation energy when concentration increases?

  It decreases
• How do shaking vinegar and baking soda more strongly affect activation energy?

  It increases concentration, thus decreasing activation energy
• What is activation energy?

  The minimum energy to start a reaction
• How does profile A compare to profile B in terms of activation energy?

  Profile A has higher activation energy than profile B.
• What is the relationship between the activation energy and the enthalpy change shown in the graph?

  The enthalpy change is less than 0
• What happens to the reaction rate when activation energy is higher?

  The reaction rate decreases.
• How does collision frequency affect reaction rates?

  More collisions increase chances of successful reactions
• How does activation energy affect the rate of a chemical reaction?

  Higher activation energy slows the reaction
• How does collision theory explain the necessity of energy in chemical reactions?

  Energy is needed to overcome activation barriers.
• Why are not all collisions successful in forming products?

  Particles need correct orientation and energy.
• In an exothermic reaction (diagram A), how does the energy of the reactants compare to the energy of the products?

  Reactants have higher energy