Catalysts - AP Chemistry

1. What is the active site in enzyme catalysis?

   The active site is the region of an enzyme where substrate binds. This specific binding site determines the enzyme's catalytic specificity.

2. Does a catalyst alter the equilibrium constant of a reaction?

   No, a catalyst does not change the equilibrium constant. Catalysts only affect reaction rates, not the thermodynamic equilibrium position.

3. Does a catalyst change the reaction mechanism?

   Yes, a catalyst provides an alternative reaction mechanism. The mechanism involves the catalyst in intermediate steps.

4. What is meant by 'catalyst poisoning'?

   Deactivation of a catalyst by impurities. Poisoning reduces or eliminates the catalyst's ability to function effectively.

5. What is the role of a promoter in catalysis?

   A substance that enhances the activity of a catalyst. Promoters improve catalyst performance without being catalysts themselves.

6. Identify an example of a catalyst in an everyday product.

   Platinum in catalytic converters of vehicles. It converts toxic exhaust gases into less harmful substances.

7. Identify a common industrial catalyst used in the Haber process.

   Iron is used as a catalyst in the Haber process. Iron catalyzes the synthesis of ammonia from nitrogen and hydrogen gases.

8. Identify the effect of a catalyst on activation energy.

   A catalyst lowers the activation energy of a reaction. This enables reactions to proceed faster at the same temperature.

9. What is the function of a catalyst in a redox reaction?

   A catalyst provides a lower-energy pathway for electron transfer. It facilitates electron transfer between oxidizing and reducing agents.

10. What is an enzyme in the context of catalysis?

    An enzyme is a biological catalyst. Enzymes are proteins that catalyze biochemical reactions in living organisms.

11. What is the effect of a catalyst on the rate constant $k$?

    A catalyst increases the rate constant $k$. Higher $k$ values result from the lower activation energy pathway.

12. What is the turnover number in catalysis?

    The number of substrate molecules converted per catalyst molecule per unit time. This measures catalytic efficiency and activity level.

13. What is the role of a support in heterogeneous catalysis?

    A support provides a surface for the catalyst to disperse. Supports increase surface area and prevent catalyst particle aggregation.

14. Do catalysts affect the overall stoichiometry of a reaction?

    No, catalysts do not affect the overall stoichiometry. Catalysts change reaction pathways but not the balanced chemical equation.

15. What does the term 'catalytic efficiency' refer to?

    The ratio of the rate constant of catalyzed reaction to uncatalyzed reaction. This quantifies how much a catalyst accelerates the reaction rate.

16. How does a catalyst affect the time required to reach equilibrium?

    A catalyst reduces the time required to reach equilibrium. Faster kinetics mean equilibrium is achieved more quickly.

17. What is a catalytic cycle?

    A sequence of steps involving a catalyst that regenerates the catalyst. The catalyst is consumed and regenerated in a repeating sequence.

18. Does a catalyst change the enthalpy change ($\triangle H$) of a reaction?

    No, a catalyst does not change the enthalpy change. Catalysts affect kinetics but not thermodynamic properties like $\Delta H$.

19. Identify an example of a catalyst in an everyday product.

    Platinum in catalytic converters of vehicles. It converts toxic exhaust gases into less harmful substances.

20. What is a homogeneous catalyst?

    A catalyst in the same phase as the reactants. Both catalyst and reactants exist in the same state of matter.

21. What is an enzyme in the context of catalysis?

    An enzyme is a biological catalyst. Enzymes are proteins that catalyze biochemical reactions in living organisms.

22. Does a catalyst change the enthalpy change ($\triangle H$) of a reaction?

    No, a catalyst does not change the enthalpy change. Catalysts affect kinetics but not thermodynamic properties like $\Delta H$.

23. What is the primary role of a catalyst in a reaction mechanism?

    To lower the activation energy and accelerate the reaction. Catalysts enable faster reaction rates by reducing energy barriers.

24. What type of catalysis involves an enzyme?

    Biocatalysis involves enzymes. Enzymes are biological catalysts that accelerate metabolic reactions.

25. What is the effect of temperature on catalytic activity?

    Increasing temperature generally increases catalytic activity. Higher temperatures provide more kinetic energy for catalyst-reactant interactions.

26. Does a catalyst change the enthalpy change ($\triangle H$) of a reaction?

    No, a catalyst does not change the enthalpy change. Catalysts affect kinetics but not thermodynamic properties like $\Delta H$.

27. Identify one advantage of using catalysts in industrial processes.

    Catalysts can increase efficiency and reduce energy consumption. They enable faster reactions at lower temperatures, saving energy costs.

28. Do catalysts affect the overall stoichiometry of a reaction?

    No, catalysts do not affect the overall stoichiometry. Catalysts change reaction pathways but not the balanced chemical equation.

29. What is 'catalytic selectivity'?

    The ability of a catalyst to direct a reaction to a specific product. Selective catalysts favor formation of desired products over side products.

30. Does a catalyst alter the equilibrium constant of a reaction?

    No, a catalyst does not change the equilibrium constant. Catalysts only affect reaction rates, not the thermodynamic equilibrium position.

31. What is the effect of temperature on catalytic activity?

    Increasing temperature generally increases catalytic activity. Higher temperatures provide more kinetic energy for catalyst-reactant interactions.

32. What is 'catalyst regeneration'?

    The process by which a catalyst is restored to its original state. This allows the catalyst to be reused multiple times.

33. Define 'autocatalysis'.

    A reaction in which the product acts as a catalyst. The product accelerates its own formation by catalyzing the reaction.

34. What is the definition of a catalyst in chemistry?

    A substance that increases reaction rate without being consumed. It speeds up reactions by providing an alternative pathway but remains unchanged after the reaction.

35. What is 'induced fit' in enzyme catalysis?

    A model where the enzyme changes shape to bind the substrate. The enzyme structure adjusts upon substrate binding for optimal catalysis.

36. What is the active site in enzyme catalysis?

    The active site is the region of an enzyme where substrate binds. This specific binding site determines the enzyme's catalytic specificity.

37. How does a catalyst affect the rate of a reaction?

    A catalyst increases the rate of a reaction. It provides an alternative pathway with lower activation energy.

38. What is the role of a support in heterogeneous catalysis?

    A support provides a surface for the catalyst to disperse. Supports increase surface area and prevent catalyst particle aggregation.

39. Does a catalyst change the reaction mechanism?

    Yes, a catalyst provides an alternative reaction mechanism. The mechanism involves the catalyst in intermediate steps.

40. What is the principle behind the use of catalysts in green chemistry?

    To reduce the need for energy and minimize waste production. Catalysts enable more efficient, environmentally friendly chemical processes.

41. Identify the effect of a catalyst on activation energy.

    A catalyst lowers the activation energy of a reaction. This enables reactions to proceed faster at the same temperature.

42. What is the role of a support in heterogeneous catalysis?

    A support provides a surface for the catalyst to disperse. Supports increase surface area and prevent catalyst particle aggregation.

43. What is 'catalyst regeneration'?

    The process by which a catalyst is restored to its original state. This allows the catalyst to be reused multiple times.

44. Is a catalyst consumed during a chemical reaction?

    No, a catalyst is not consumed in the reaction. It participates in the reaction but is regenerated in the final step.

45. Define 'autocatalysis'.

    A reaction in which the product acts as a catalyst. The product accelerates its own formation by catalyzing the reaction.

46. How does a catalyst affect the time required to reach equilibrium?

    A catalyst reduces the time required to reach equilibrium. Faster kinetics mean equilibrium is achieved more quickly.

47. What is a homogeneous catalyst?

    A catalyst in the same phase as the reactants. Both catalyst and reactants exist in the same state of matter.

48. What is the active site in enzyme catalysis?

    The active site is the region of an enzyme where substrate binds. This specific binding site determines the enzyme's catalytic specificity.

49. What is the turnover number in catalysis?

    The number of substrate molecules converted per catalyst molecule per unit time. This measures catalytic efficiency and activity level.

50. What is 'catalyst regeneration'?

    The process by which a catalyst is restored to its original state. This allows the catalyst to be reused multiple times.

51. Does a catalyst alter the equilibrium constant of a reaction?

    No, a catalyst does not change the equilibrium constant. Catalysts only affect reaction rates, not the thermodynamic equilibrium position.

52. Describe the role of a catalyst in a chemical reaction.

    A catalyst provides an alternative pathway with lower activation energy. This allows reactions to proceed faster without changing thermodynamic properties.

53. Identify the main difference between homogeneous and heterogeneous catalysts.

    Homogeneous catalysts are in the same phase as reactants; heterogeneous are not. Phase differences affect separation, recovery, and reaction mechanisms.

54. What is a heterogeneous catalyst?

    A catalyst in a different phase than the reactants. The catalyst exists in a different state of matter from the reactants.

55. What is an enzyme in the context of catalysis?

    An enzyme is a biological catalyst. Enzymes are proteins that catalyze biochemical reactions in living organisms.

56. Is a catalyst consumed during a chemical reaction?

    No, a catalyst is not consumed in the reaction. It participates in the reaction but is regenerated in the final step.

57. What is the 'lock and key' model in enzyme catalysis?

    A model where the enzyme and substrate fit perfectly together. This model assumes rigid, complementary shapes between enzyme and substrate.

58. What is the 'lock and key' model in enzyme catalysis?

    A model where the enzyme and substrate fit perfectly together. This model assumes rigid, complementary shapes between enzyme and substrate.

59. Identify a property that distinguishes enzymes from inorganic catalysts.

    Enzymes are specific for particular reactions. Enzyme specificity contrasts with the broader activity of inorganic catalysts.

60. What is the definition of a catalyst in chemistry?

    A substance that increases reaction rate without being consumed. It speeds up reactions by providing an alternative pathway but remains unchanged after the reaction.

61. How does a catalyst affect the time required to reach equilibrium?

    A catalyst reduces the time required to reach equilibrium. Faster kinetics mean equilibrium is achieved more quickly.

62. Identify one effect of a catalyst on reaction pathways.

    A catalyst provides an alternative reaction pathway. This alternative route has lower activation energy than the uncatalyzed reaction.

63. Identify one advantage of using catalysts in industrial processes.

    Catalysts can increase efficiency and reduce energy consumption. They enable faster reactions at lower temperatures, saving energy costs.

64. What is 'induced fit' in enzyme catalysis?

    A model where the enzyme changes shape to bind the substrate. The enzyme structure adjusts upon substrate binding for optimal catalysis.

65. Does a catalyst change the reaction mechanism?

    Yes, a catalyst provides an alternative reaction mechanism. The mechanism involves the catalyst in intermediate steps.

66. How does a catalyst affect the Gibbs free energy ($\triangle G$) of a reaction?

    A catalyst does not affect the Gibbs free energy change. Catalysts change kinetics but not the overall energy change of reactions.

67. What is the effect of a catalyst on the rate constant $k$?

    A catalyst increases the rate constant $k$. Higher $k$ values result from the lower activation energy pathway.

68. What is the function of a catalyst in a redox reaction?

    A catalyst provides a lower-energy pathway for electron transfer. It facilitates electron transfer between oxidizing and reducing agents.

69. Identify the main difference between homogeneous and heterogeneous catalysts.

    Homogeneous catalysts are in the same phase as reactants; heterogeneous are not. Phase differences affect separation, recovery, and reaction mechanisms.

70. Identify one advantage of using catalysts in industrial processes.

    Catalysts can increase efficiency and reduce energy consumption. They enable faster reactions at lower temperatures, saving energy costs.

71. Do catalysts affect the overall stoichiometry of a reaction?

    No, catalysts do not affect the overall stoichiometry. Catalysts change reaction pathways but not the balanced chemical equation.

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