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A catalyst is a substance that initiates or speeds up the rate of a chemical reaction without being impacted chemically. A catalyst can be utilized in a process and then recovered and reused once the reaction is complete. Catalysis is the process or action of using a catalyst to accelerate the pace of a reaction. The study of reaction rates and how they change when they are altered experimentally is known as kinetics.
- Which of the following facts about catalysts is incorrect?
a) Catalysts reduce a reaction’s activation energy.
b) Catalysts increase the number of reactions that can happen spontaneously
c) Catalysts enhance the number of molecules with enough energy to break beyond the activation energy barrier.
d) Catalysts offer a different technique to get from reactant to product.
Answer: (b) Catalysts increase the number of reactions that can happen spontaneously because Catalysts improve the rate of reaction by giving a lower-activation-energy alternative reaction pathway. Catalysts, on the other hand, have no effect on things like enthalpy, entropy, or the spontaneity of a reaction.
- Which one of the following is not a catalysis category?
a) Homogeneous
b) Heterogeneous
c) Artificial
d) Enzymatic
Answer: (c) Artificial because Catalysis is divided into four categories: homogeneous, heterogeneous, auto, and enzymatic. Catalysis does not include the term “artificial.”
- The factor that influences a heterogeneous catalyst’s activity is ___________
a) Total surface area only
b) The number of active sites per unit amount of catalyst only
c) Method of preparation, prior treatment only
d) Total surface area, number of active sites and method of preparation
Answer: (d) Total surface area, number of active sites and method of preparation because Total surface area, number of active sites per unit amount of catalyst, technique of manufacture, and prior treatment are the elements that determine the activity of a heterogeneous catalyst.
- Which of the following does not happen at the phase transition?
a) Crystallization
b) Heterogeneous catalysis
c) Homogeneous catalysis
d) Corrosion
Answer: (c) Homogeneous catalysis because a catalyst is a substance that boosts the rate of a reaction but does not change chemically during the process. The reactants and catalyst are in the same phase in homogeneous catalysis (i.e., liquid or gas).
- The activity of the catalyst is reduced by the promoter.
a) True
b) False
Answer: (b) False because a catalytic promoter is a chemical that boosts the activity of a catalyst without actually acting as one.
- Which of the statements below is incorrect?
a) The surface area of a solid catalyst determines its efficiency.
b) Catalysts work by giving an alternative path for the reaction that has a lower activation energy.
c) Catalyst reduces the energy required to activate the forward reaction while having no effect on the energy required to activate the backward reaction.
d) The overall enthalpy change of the reaction is unaffected by the catalyst.
Answer: (c) Catalyst reduces the energy required to activate the forward reaction while having no effect on the energy required to activate the backward reaction because a catalyst creates a lower-activation-energy alternative pathway for the reaction. When the activation energy is low, more reactant particles have adequate energy to react, resulting in a faster reaction.
- Which of the following is a poison that catalyzes a reaction??
a) Potassium nitrate
b) Aluminum nitrate
c) Aluminum oxide
d) Chlorine
Answer: (c) Aluminum oxide because Aluminum oxide is well-known for its sophisticated qualities, and it is mostly used to prevent corrosion. It absorbs moisture and has a high retentivity, making it an excellent catalytic poison.
- As a catalytic promoter, which of the following is used??
a) Chlorine
b) Nitrate
c) Bromine
d) Helium
Answer: (b) Nitrate because A promoter is used to speed up the rate of equilibrium. In the case of nitrate molecules, we know that nitrogen possesses promoting qualities. As a result, they can operate as good reaction promoters.
- For the following reaction, which of the following is utilized as a catalyst?
N2 + 3H2 ⟶ 2NH3
a) Zinc
b) Chlorine
c) Platinum
d) Water
Answer: (c) Platinum because because the equilibrium valencies of nitrogen and noble metals components are the same, we can see that one will promote the other and vice versa. As a result, the nitrogen molecule is ideal for platinum molecules.
- For the reaction, which of the following is utilized as a catalytic poison?
SO2 + O2 ⟶ 2SO3
a) Platinum
b) Bromine
c) Magnesium
d) Silver
Answer: (a) Platinum because, despite the fact that nitrogen is utilized as a promoter, platinum diminishes its activity, lowering the pace of equilibrium reaction in the aforesaid reaction.
- Reactions in Zeolite catalysts are influenced by a variety of factors
a) Pores
b) Apertures
c) Size of cavities
d) All of these
Answer: (d) All of these because it’s a catalyst that’s shape-selective.
- In a reversible reaction, a catalyst’s job is to accelerate the reaction:
a) Increase the rate of forward reaction
b) Decrease the rate of backward reaction
c) Alter the equilibrium constant of the reaction
d) Allow the equilibrium to be achieved quickly
Answer: (d) Allow the equilibrium to be achieved quickly because an increase in forward reaction rate by a catalyst for a reaction in equilibrium leads to an increase in product concentration, and thus the rate of backward reaction increases to the same magnitude, allowing the equilibrium to be reached fast.
- When a catalyst is used in a system
a) Value of equilibrium constant is decreased
b) The rate of forward reaction is increased and that of backward reaction is decreased
c) Equilibrium concentrations are unchanged
d) Equilibrium concentrations are increased
Answer: (c) Equilibrium concentrations are unchanged because the equilibrium constant is never changed by a catalyst.
- When a catalyst is used in a reaction, which of the following changes?
a) Heat of reaction
b) Product of reaction
c) Equilibrium constant
d) Activation energy
Answer: (d) Activation energy because when a catalyst is utilised in a reaction, the activation energy changes.
