How does the use of a catalyst affect the activation energy of a chemical reaction?
A.
It increases the activation energy required for the reaction.
B.
It decreases the activation energy required for the reaction.
C.
It has no effect on the activation energy required for the reaction.
D.
It increases the rate of reaction but has no effect on the activation energy.
The Correct Answer and Explanation is:
The correct answer is B. It decreases the activation energy required for the reaction.
Explanation:
A catalyst is a substance that accelerates a chemical reaction without being consumed in the process. It achieves this by providing an alternative reaction pathway with a lower activation energy compared to the non-catalyzed reaction. The concept of activation energy is central to understanding how catalysts work.
Activation Energy: Activation energy is the minimum energy that reactant molecules must possess for a chemical reaction to occur. It represents the energy barrier that must be overcome for the reactants to transform into products. Higher activation energy means that fewer molecules will have enough energy to react, which slows down the reaction rate.
Role of a Catalyst: A catalyst provides an alternative reaction mechanism that has a lower activation energy. By lowering the activation energy, the catalyst increases the number of reactant molecules that have sufficient energy to undergo the reaction. This leads to an increased reaction rate. However, it’s important to note that a catalyst does not alter the equilibrium position of the reaction; it only helps the system reach equilibrium faster by accelerating both the forward and reverse reactions equally.
Mechanism: The catalyst often interacts with the reactants to form an intermediate complex. This intermediate is typically less energetic than the transition state of the uncatalyzed reaction, thus requiring less energy to reach it. The intermediate then breaks down to yield the products, and the catalyst is regenerated to participate in another reaction cycle.
Effectiveness: The effectiveness of a catalyst is measured by its ability to lower the activation energy and thus increase the reaction rate. Catalysts are crucial in both industrial and biological processes. For example, enzymes are biological catalysts that lower the activation energy of biochemical reactions in living organisms, allowing them to proceed at rates necessary for life.
In summary, catalysts function by providing an alternative pathway with lower activation energy, thereby increasing the reaction rate and enhancing the efficiency of chemical processes.