Problem 77 - A Complete Resource Book in Chemistry for JEE Main

Question

In case of auto catalysis (a) reactant catalyses (b) product catalyses (c) solvent catalyses (d) heat produced in the reaction catalyses

Step-by-Step Solution

Answer

In autocatalysis, (b) product catalyses the reaction.

Step 1: Understanding Autocatalysis

Autocatalysis occurs when a product of the reaction serves as a catalyst for the reaction itself, thereby increasing the reaction rate.

Step 2: Analyzing the Options

We need to evaluate each option to determine which components can act as an autocatalyst.

Step 3: Assessing Each Option

(a) Reactant catalyses - Reactants typically participate in the reaction but do not necessarily act as a catalyst. (b) Product catalyses - This option describes autocatalysis, as a product of the reaction serves as a catalyst. (c) Solvent catalyses - Solvents can sometimes influence reaction rates but do not fit the definition of autocatalysis. (d) Heat produced in the reaction catalyses - Heat can increase the reaction rate but does not qualify as a catalyst.

Step 4: Determining the Correct Answer

Since autocatalysis involves the product of the reaction catalyzing the reaction, the correct answer is (b) - product catalyses.

Key Concepts

Understanding Reaction Mechanisms

In order to understand how autocatalysis works, it's important to grasp the concept of a reaction mechanism. A reaction mechanism is a detailed step-by-step description of how a chemical reaction occurs. It explains which bonds break and form, what intermediates are created along the way, and how the overall transformation from reactants to products takes place.
Think of it as a map that details each stage of a journey. In a chemical reaction, these pathways can include multiple steps, each contributing to the final outcome. By understanding the reaction mechanism, scientists can gain insights into the efficiency and speed of a reaction, helping them to predict and control it more effectively.

• Reaction mechanisms provide a detailed pathway from reactants to products.
• An understanding of the mechanism can help predict reaction outcomes and improve control.
• Intermediates and transition states play key roles in determining the reaction steps.

Role of Catalysts in Chemical Reactions

In chemical reactions, catalysts play a crucial role by speeding up the reaction without being consumed in the process. They work by providing an alternative reaction pathway with a lower activation energy, which is the minimum energy needed for a reaction to occur.
This can make a once sluggish reaction much faster. Catalysts are not used up, which means they can continue to catalyze subsequent reactions. In the context of autocatalysis, the catalyst is one of the products, which then helps speed up the reaction itself.

• Catalysts lower the activation energy required for reactions.
• They remain unchanged after the reaction, allowing continuous use.
• In autocatalysis, the reaction product acts as its own catalyst.

Enhancing Reaction Rates

Enhancing reaction rates is key to controlling chemical processes efficiently. There are several factors that can influence how fast a reaction occurs. Temperature is one such factor, as it generally increases the speed of reactions by providing the necessary energy to break chemical bonds.
However, relying solely on temperature isn't always practical. This is where catalysts, including those in autocatalytic reactions, become extremely valuable. By lowering the activation energy, catalysts offer a more efficient way to boost reaction rates without the need to increase temperature drastically.

• Increasing temperature typically speeds up chemical reactions.
• Catalysts provide an efficient pathway without extensive energy input.
• Autocatalysis specifically utilizes a product to accelerate the process.