5.2 Reaction profiles

• A reaction profile is a graphical representation that illustrates the energy changes during a chemical reaction
• In an exothermic reaction, energy is released, resulting in a negative overall energy change.


  True
• Match the feature of a reaction profile with its description:

  Reactants ↔️ Starting substances in the reaction

  Products ↔️ Substances formed at the end of the reaction

  Activation Energy ↔️ Minimum energy required to start the reaction
• The reactants in a reaction profile are shown at the initial energy level
• In an exothermic reaction, the products have lower energy than the reactants.


  True
• The overall energy change in a reaction is the difference in energy between the reactants and the products
• Match the reaction type with its overall energy change:

  Exothermic ↔️ Negative

  Endothermic ↔️ Positive
• Arrange the key features of a reaction profile in the correct order:

  1️⃣ Reactants

  2️⃣ Activation Energy

  3️⃣ Transition State

  4️⃣ Overall Energy Change

  5️⃣ Products
• Endothermic reactions have a positive overall energy change because energy is absorbed


  True
• In a reaction profile, the products are shown at the final energy level
• Match the component of a reaction profile with its description:

  Reactants ↔️ Starting substances

  Transition State ↔️ High-energy intermediate

  Products ↔️ Substances formed at end
• A higher activation energy results in a slower reaction rate
• What does enthalpy change (ΔH) represent in a chemical reaction?

  Overall energy change
• Energy is absorbed from the surroundings in an endothermic reaction

  True
• What is the role of the transition state in a reaction profile?

  Highest-energy state
• The activation energy is the energy required for reactants to reach the transition state
• What is a reaction profile?

  Graphical representation of energy changes
• The overall energy change in a reaction is the difference between the energy of reactants and products.


  True
• In endothermic reactions, energy is absorbed
• Describe the energy diagram for an exothermic reaction.

  Energy decreases from reactants to products
• The transition state in a reaction profile represents the point of highest energy.


  True
• What is the role of the transition state in a chemical reaction?

  High-energy intermediate
• A higher activation energy indicates a slower reaction rate.


  True
• A higher activation energy results in a slower reaction rate.
• A negative enthalpy change indicates that energy is released in the reaction.

  True
• In an endothermic reaction, the energy level of products is higher than that of reactants.
• What is the effect of exothermic reactions on the surroundings?

  Temperature increase
• The factors affecting reaction rates influence how quickly reactants are converted into products.
• Endothermic reactions cause a temperature decrease in the surroundings.


  True
• How does heating reactants affect the reaction rate?

  Increases rate
• Match the factor affecting reaction rate with its effect:

  Pressure ↔️ Increases collision frequency of gases

  Surface Area ↔️ Provides more sites for collisions

  Catalysts ↔️ Lowers activation energy
• In a reaction profile, the catalyzed reaction has a lower peak compared to the uncatalyzed
• What does the overall energy change (ΔH) represent in a reaction profile?

  Energy difference between reactants and products
• In a reaction profile, the transition state represents the highest energy point
• What is the role of activation energy in a chemical reaction?

  Enables bond breaking and forming
• The activation energy is the energy difference between the reactants and the highest point of the transition
• Higher activation energy results in a faster reaction rate.

  False
• What role does activation energy play in a chemical reaction?

  Enables bond breaking and forming
• The activation energy is represented as the peak on a reaction profile.


  True
• The activation energy is the minimum energy needed to start a chemical reaction