[Q&A Question 161] 2016.09.28
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【Q&A Question 161】September 28, 2016: What are the characteristics of catalysts during reactions? The answer key can be seen after responding; scoring is based on identifying the key points. Answer: (1) The catalyst reacts with the reactants to form intermediate compounds, thereby altering the reaction pathway ； (2) The role of the catalyst is to shorten the time required to reach equilibrium, but it cannot change the equilibrium state ； (3) The catalyst is selective.
It changes the reaction rate (speeding it up or slowing it down), yet its own chemical properties remain unchanged before and after the reaction, as does its amount; in other words, it is not consumed at all and can be considered as not participating in the reaction. However, sometimes a reaction takes place in several steps, and some catalysts participate in the first step before being regenerated in subsequent steps, so that their amount remains unchanged throughout the overall reaction
The characteristics of a catalyst during a reaction are: first, it alters the reaction pathway. The second is to change the activation energy of the reaction. The third change is the reaction rate constant. But it does not change the chemical equilibrium of the reaction.
①Catalysis alters the reaction rate by changing the reaction pathway and reducing the reaction activation energy； ②Catalysis cannot change thermodynamic equilibrium ； ③Catalysts are selective in accelerating reactions ； ④Catalysts have a lifespan.
The catalyst itself participates in the reaction; its mass remains unchanged before and after the reaction, as does its composition. Catalysts can change the rate of chemical reactions.
The catalyst itself participates in the reaction; its mass remains unchanged before and after the reaction, as does its composition. Catalysts can alter the rate of chemical reactions; those that increase the reaction rate are called catalysts, while those that decrease it are called inhibitors.
Catalysts can only facilitate reactions that are thermodynamically feasible; they cannot enable reactions that are thermodynamically impossible； A catalyst can only change the rate of a chemical reaction, not the position of the chemical equilibrium ； Catalysts can reduce the activation energy of a reaction and alter its mechanism ； Catalysts are selective for reactions.
The reaction speed increases; heat is released during hydrogenation, causing the temperature to rise, which in turn leads to increased hydrogen consumption
It does not participate in the reaction, its properties do not change, and it neither accelerates nor slows down the reaction rate
A catalyst can only change the rate of a chemical reaction, not the position of the chemical equilibrium； Catalysts can reduce the activation energy of a reaction and alter its mechanism.
1. The catalyst reacts with the reactants to form intermediate compounds, thereby altering the reaction pathway. 2. The role of a catalyst is to shorten the time required to reach equilibrium, but it cannot change the equilibrium state