Problem 32 - A Complete Resource Book in Chemistry for JEE Main

Question

The function of catalyst in chemical reaction is to (a) increase the product (b) decrease the product (c) accelerate the rate of reaction (d) increase the reactants

Step-by-Step Solution

Answer

The function of a catalyst in a chemical reaction is to accelerate the rate of reaction (c).

Step 1: Understanding the Role of a Catalyst

A catalyst is a substance that increases the rate of a chemical reaction without undergoing any permanent chemical change itself. It works by providing an alternative reaction pathway with a lower activation energy.

Step 2: Analyzing the Options

Options (a) and (b) refer to changes in the amount of product, which is not the primary role of a catalyst. Option (d) mentions an increase in reactants, which is also not directly related to the role of a catalyst.

Step 3: Identifying the Effect on Reaction Rate

The primary function of a catalyst is to accelerate the reaction rate, as mentioned in option (c), by lowering the activation energy required for the reaction to proceed.

Step 4: Conclusion

Since a catalyst accelerates the reaction rate without being consumed or altering the reactants' and products' amounts, the correct answer to the function of a catalyst is option (c): it accelerates the rate of reaction.

Key Concepts

Activation Energy

Activation energy is a key concept in understanding how reactions occur. It refers to the minimum amount of energy needed to initiate a chemical reaction. Without sufficient energy, molecules cannot overcome the initial energy barrier, and the reaction will not proceed.

Think of activation energy as a hurdle that reactants must jump over to become products. The height of this hurdle determines how easily a reaction can begin. High activation energy means the reaction proceeds slowly or not at all, while low activation energy allows the reaction to occur more easily.

This is where catalysts come into play. A catalyst provides an alternate pathway with a lower activation energy. By lowering this energy barrier, catalysts make it easier for the reaction to occur, even at lower temperatures. This increase in reaction feasibility is a fundamental reason why catalysts are so crucial in chemical reactions.

Chemical Reaction Rate

The rate of a chemical reaction indicates how quickly reactants are converted into products. Various factors influence this rate, including temperature, concentration, and the presence of a catalyst.

A faster reaction rate means reactants transform into products more swiftly. This is highly desirable in industrial processes where time efficiency is critical. Catalysts are often employed to increase reaction rates without being consumed in the reaction itself.

For example, in an industrial setting, the Haber process uses a catalyst to speed up the production of ammonia from nitrogen and hydrogen gases. Without a catalyst, the reaction would proceed too slowly to be economically viable. Thus, understanding and manipulating the rate of chemical reactions via catalysts is vital in both laboratory and industrial applications.

Alternative Reaction Pathway

An alternative reaction pathway is a different route that a reaction can take to form products, facilitated by a catalyst. This new pathway typically requires less activation energy compared to the original pathway, allowing the reaction to proceed more easily.

Think of it as taking a shortcut on a journey. The destination (products) remains the same, but the road (reaction pathway) is smoother and requires less energy to travel.

By offering this alternative route, catalysts enhance reaction efficiency and rate. This is particularly crucial in reactions where the original pathway involves high energy costs. Through this mechanism, catalysts not only speed up reactions but can also make them possible under milder conditions, which might not be achievable otherwise. Understanding this concept is essential for grasping the multifaceted role of catalysts in chemical processes.