Problem 73 - A Complete Resource Book in Chemistry for JEE Main

Question

In the reaction \(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}(\mathrm{~s})+\mathrm{H}_{2} \mathrm{O}(\mathrm{1}) \stackrel{\mathrm{Dal} \mathrm{H}_{2} \mathrm{SO}}{\leftrightarrow} \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(\mathrm{aq})\) \(+\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(\mathrm{aq})\) dilute \(\mathrm{H}_{2} \mathrm{SO}_{4}\) acts as (a) homogeneous catalyst (b) heterogenous catalyst (c) heterogeneous reactant (d) homogeneous reactant

Step-by-Step Solution

Answer

The dilute \(\mathrm{H}_{2}\mathrm{SO}_{4}\) acts as a homogeneous catalyst.

Step 1: Identify Reaction Components

In the given reaction, sucrose (0_{12}\mathrm{H}_{22}\mathrm{O}_{11}) reacts with water in the presence of dilute \( 0_{2}\mathrm{SO}_{4} \) to produce glucose \((\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}))\). The role of sulfuric acid needs to be determined.

Step 2: Understand Catalyst Definitions

Catalysts are substances that increase the rate of a reaction without being consumed in the process. A homogeneous catalyst exists in the same phase as the reactants, while a heterogeneous catalyst is in a different phase.

Step 3: Analyze the Reaction Phases

In this reaction, sucrose and water are initially in solid and liquid phases, respectively. The sulfuric acid is dilute and thus aqueous, implying it shares the same phase as the reactant solution.

Step 4: Determine the Role of Dilute \(\mathrm{H}_{2}\mathrm{SO}_{4}\)

Since dilute \(\mathrm{H}_{2}\mathrm{SO}_{4}\) is in the same aqueous phase as the reactants and facilitates the reaction without being consumed, it functions as a homogeneous catalyst.

Key Concepts

Homogeneous Catalyst in Chemical Reactions

In many chemical reactions, a catalyst is used to speed up the process without being consumed. One common type of catalyst is the homogeneous catalyst. This type of catalyst is in the same phase as the reactants, making it blend seamlessly with them and ensuring an even distribution throughout the reaction mixture. This uniformity allows the catalyst to effectively facilitate the chemical changes necessary to complete the reaction. For instance, in various organic reactions, such as the hydrolysis of esters or carbohydrates, homogeneous catalysts are often employed to drive the desired outcomes rapidly.

• A homogeneous catalyst is particularly useful in liquid-liquid systems, where both reactants and catalysts can mix well.
• This results in a more efficient and controllable reaction.

The main advantage of homogeneous catalysts lies in their ability to increase the reaction rate significantly while maintaining consistency across the reaction mixture.

Sucrose Hydrolysis: Breaking Down the Sugar

Sucrose hydrolysis is a common reaction where sucrose, a sugar composed of glucose and fructose, is broken down into its constituent monosaccharides. This process is important in both biological systems and industrial applications. During hydrolysis, sucrose reacts with water to produce glucose and fructose. In our example reaction, dilute sulfuric acid facilitates this breakdown.

• The reaction is represented by sucrose (\(\mathrm{C}_{12}\mathrm{H}_{22}\mathrm{O}_{11}\)) reacting with water (\(\mathrm{H}_{2}\mathrm{O}\)) to yield two glucose molecules (\(\mathrm{C}_{6}\mathrm{H}_{12}\mathrm{O}_{6}\)).
• Due to the complex nature of sucrose, a catalyst like sulfuric acid is beneficial to reduce the energy barrier for the reaction, making it proceed faster.

This reaction not only helps us understand sugar metabolism in organisms but also serves industrial purposes, like preparing invert sugar syrup, often used in food processing.

Reaction Phases Analysis in Catalytic Processes

Understanding the phases of substances involved in a reaction is crucial, especially when determining the type of catalyst used. In our reaction, it's critical to note that sucrose is a solid at the beginning, while water and sulfuric acid are liquids. When we refer to phases in chemistry, we're considering the physical state, such as solid, liquid, or gas.

• The reaction phase analysis focuses on the interaction between reactants and catalysts, highlighting the importance of phase homogeneity for reaction efficiency.
• Since both water and dilute sulfuric acid are in the liquid phase, mixing and reaction occur smoothly.

The expected outcome of this analysis is to confirm that the catalyst, being homogeneous, matches the phase of the reactants. This matching enhances the reaction dynamics as it ensures the catalyst can work without any phase barriers. Hence, in our specific scenario, sulfuric acid qualifies as a homogeneous catalyst due to its same-phase interaction with the reactants.