All flashcards
Flashcard 1: How is the stability of a species related to its energy in a profile?
Answer: Lower energy indicates greater stability. Species at lower energy positions are more thermodynamically stable.
Flashcard 2: What does a reaction energy profile plot on the x-axis?
Answer: Reaction progress. Shows how far the reaction has proceeded from start to finish.
Flashcard 3: Determine the overall reaction energy change from a provided profile.
Answer: Use ΔE=Eproducts−Ereactants. Subtract reactant energy from product energy for net change.
Flashcard 4: Which species in a reaction energy profile is typically unstable?
Answer: The transition state is typically unstable. It exists at maximum energy and quickly decomposes to products or reactants.
Flashcard 5: Which part of the energy profile indicates an exothermic reaction?
Answer: Products have lower energy than reactants. Energy is released when products are more stable than reactants.
Flashcard 6: Identify which step is rate-limiting given activation energies.
Answer: Step with the highest activation energy. The slowest step has the largest energy barrier to overcome.
Flashcard 7: Which factor does not affect the position of equilibrium in a chemical reaction?
Answer: Catalyst. Catalysts change reaction rate but not equilibrium position.
Flashcard 8: Define the term 'enthalpy change' in a chemical reaction.
Answer: The heat change at constant pressure. Measures energy change when pressure remains constant during reaction.
Flashcard 9: How does a catalyst affect the transition state energy?
Answer: It lowers the energy of the transition state. Provides an alternative pathway with reduced energy barrier.
Flashcard 10: Determine the intermediate energy level given a reaction profile.
Answer: Energy at the valley between peaks. Intermediates exist at local minima between transition state peaks.
Flashcard 11: Find the energy of the transition state from a given profile.
Answer: Energy at the peak of the curve. The transition state occurs at the maximum energy point.
Flashcard 12: Evaluate if a reaction is exothermic from a given energy profile.
Answer: Reactants have higher energy than products. Final energy level below initial level indicates exothermic reaction.
Flashcard 13: Identify the step with the smallest activation energy in a profile.
Answer: The step with the lowest peak. The shortest peak represents the easiest step to complete.
Flashcard 14: How is the stability of a species related to its energy in a profile?
Answer: Lower energy indicates greater stability. Species at lower energy positions are more thermodynamically stable.
Flashcard 15: State the relationship between activation energy and reaction rate.
Answer: Higher activation energy generally means slower reaction rate. Larger energy barriers require more thermal energy to overcome.
Flashcard 16: Identify the peak with the highest energy in a multistep reaction profile.
Answer: The peak of the rate-determining step. The highest transition state determines the overall reaction rate.
Flashcard 17: Which reaction step is the slowest in a multistep process?
Answer: The rate-determining step. The step with highest activation energy limits overall reaction rate.
Flashcard 18: What does the height of the energy barrier in a profile indicate?
Answer: The activation energy of the reaction. Higher barriers require more energy to overcome for reaction.
Flashcard 19: What is the significance of the highest peak in a multistep energy profile?
Answer: It represents the rate-determining step. The tallest peak controls the overall reaction rate.
Flashcard 20: What does the area under a reaction energy profile curve represent?
Answer: It is not directly meaningful; focus on energy changes. The area has no physical significance in energy profiles.
Flashcard 21: Identify the rate-determining step in a multistep reaction.
Answer: The step with the highest activation energy. The slowest step controls the overall reaction rate.
Flashcard 22: What is the role of a catalyst in a multistep reaction energy profile?
Answer: It lowers the activation energy of the reaction. Provides an alternative pathway with a lower energy barrier.
Flashcard 23: Which part of the energy profile indicates an endothermic reaction?
Answer: Products have higher energy than reactants. Energy is absorbed when products are less stable than reactants.
Flashcard 24: Identify the energy change if reactants have higher energy than products.
Answer: Exothermic reaction. Energy decreases from reactants to products, releasing heat.
Flashcard 25: What is the effect of a catalyst on the overall reaction energy change?
Answer: It does not affect the overall energy change. Catalysts only affect reaction rate, not thermodynamic properties.
Flashcard 26: What is the nature of the reaction if ΔH<0?
Answer: Exothermic reaction. Negative enthalpy change indicates energy release to surroundings.
Flashcard 27: How does the energy profile change with a catalyst addition?
Answer: Lower peaks for each step. Catalyst provides alternative pathway with reduced energy barriers.
Flashcard 28: What does a reaction energy profile plot on the y-axis?
Answer: Potential energy. Energy represents the stored chemical potential energy of species.
Flashcard 29: What is the activation energy in a reaction energy profile?
Answer: The energy difference between reactants and the transition state. This represents the energy barrier that must be overcome for the reaction to proceed.
Flashcard 30: Identify the part of the energy profile that represents the activation complex.
Answer: The peak of the energy curve. The activation complex is the same as the transition state.