Question

Which of the following statement is/are correct regarding a catalyst? a. Decreases the activation energy. b. Increases the average kinetic energy of reacting molecules. c. Increases the frequency of collision of reacting. d. Alters the reaction mechanism.

Short answer

Statements a and d are correct.

Step-by-step solution

Understanding a Catalyst's Role

A catalyst is a substance that speeds up a chemical reaction without itself being consumed in the process. To determine which statements are correct, we must consider the various effects a catalyst has on reactions.

Analyzing Statement a

A catalyst works by providing an alternate pathway for the reaction with a lower activation energy. This statement correctly identifies a core function of catalysts: they decrease the activation energy required for a reaction, thus speeding up the reaction. So, statement a is correct.

Evaluating Statement b

The average kinetic energy of reacting molecules is primarily determined by temperature. A catalyst does not change the energy of the individual molecules; instead, it affects the pathway and rate of reaction. Therefore, statement b is incorrect.

Considering Statement c

While catalysts affect how frequently reactions reach the transition state by lowering activation energy, they do not directly increase the frequency of molecular collisions. This is generally more related to concentration or physical state. Thus, statement c is incorrect.

Assessing Statement d

A catalyst can change the reaction mechanism because it provides an alternative pathway for the reaction that requires less energy. This implies that the sequence of steps in the reaction might alter when a catalyst is present, confirming that statement d is correct.

Key concepts

Activation Energy

Activation energy is a critical concept in understanding how chemical reactions occur. It refers to the minimum energy that reacting molecules must possess for a reaction to take place. Think of it as an energy barrier that molecules need to overcome to transform into products. Without sufficient energy, reactants remain unchanged.

Catalysts play a vital role in altering this energy landscape. They work by lowering the activation energy required for a reaction, making it easier for molecules to react. By providing an alternative pathway with a lower energy requirement, catalysts accelerate the reaction rate without being consumed in the process.

• Activation Energy is the energy barrier for reactions.
• Catalysts lower this barrier, speeding up reactions.

Catalysts do not change the energy levels of reactants or products; they merely offer a path with less resistance, thereby enhancing the reaction rate.

Reaction Mechanism

A reaction mechanism outlines the step-by-step sequence through which a chemical reaction proceeds. It's like a roadmap that shows how reactants transform into products, detailing the individual steps involved.

Catalysts significantly influence reaction mechanisms. By offering an alternate route for the reaction with a lower activation energy, catalysts effectively alter the path a reaction takes. This can lead to a change in the sequence of steps, known as the reaction mechanism. In other words, what might have been a tough path with higher energy peaks becomes more manageable with a catalyst.

• Reaction Mechanism describes the pathway of a reaction.
• Catalysts alter this path, providing easier steps with lower energy.

Understanding the modified reaction mechanisms can offer insights into how catalysts make reactions faster and more efficient.

Chemical Kinetics

Chemical kinetics deals with the rate at which a chemical reaction occurs and the factors that affect this rate. It's a study of how fast reactions happen and what influences these speeds.

The role of catalysts is central in chemical kinetics as they significantly impact reaction rates without being part of the chemical equilibrium. By lowering the activation energy, catalysts result in an increased reaction rate. They offer alternative routes for reactions, shifting the way molecules interact and reducing the time needed for reactions to complete.

• Chemical Kinetics is the study of reaction rates.
• Catalysts affect these rates by lowering activation energy.

While catalysts do not change the nature of the products and reactants, they ensure that reactions occur more quickly and efficiently. This efficiency is crucial in industrial and biochemical processes where timing is essential.