Problem 70 - A Complete Resource Book in Chemistry for JEE Main

Question

Homogeneous catalysis implies that (a) reactants and products must be in the same phase (b) reactants and catalyst must be in the same phase (c) composition of the reaction mixture must be homogeneous throughout (d) products and the catalyst must be in the same phase

Step-by-Step Solution

Answer

The correct answer is (b) reactants and catalyst must be in the same phase.

Step 1: Understand the Definition of Homogeneous Catalysis

Homogeneous catalysis refers to a catalysis process where the catalyst is in the same phase as the reactants. It is important to note that the word "phase" refers to physical states such as solid, liquid, or gas.

Step 2: Analyze the Given Options

We need to identify the characteristic of a homogeneous catalyst by examining each option: (a) states that reactants and products are in the same phase, (b) states that reactants and catalyst are in the same phase, (c) implies the reaction mixture is uniform, (d) claims that products and catalyst are in the same phase.

Step 3: Eliminate Incorrect Options

Begin by eliminating options that don't specifically relate to the definition of homogeneous catalysis: - Option (a) doesn't mention the catalyst's role. - Option (c) does not relate the reactants to the catalyst. - Option (d) incorrectly focuses on products.

Step 4: Select the Correct Option

According to the definition of homogeneous catalysis and the examination above, option (b) is the correct answer because homogeneous catalysis requires that the reactants and catalyst are in the same phase.

Key Concepts

Catalyst

A catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change. In homogeneous catalysis, this process requires the catalyst to be in the same phase as the reactants, ensuring an efficient interaction.

Catalysts work by providing an alternative reaction pathway with a lower activation energy. This allows the reactants to convert into products more easily and quickly than they would in the absence of the catalyst.

• Enzymes are biological catalysts that often operate via homogeneous catalysis in aqueous environments.
• In industrial processes, homogeneous catalysis can enhance efficiency and selectivity, reducing costs.

It's crucial to understand that even though catalysts speed up reactions, they are not consumed, meaning they can repeatedly assist in the reaction process.

Reaction Mechanism

The reaction mechanism describes the step-by-step sequence of elementary reactions by which overall chemical change occurs.

In the context of homogeneous catalysis, understanding the mechanism is essential. The catalyst interacts with the reactants in the same phase, forming an intermediate that lowers the reaction's energy requirements.

• This intermediate is often highly reactive, making it an effective catalyst.
• After forming the product, the catalyst is regenerated, allowing it to participate in subsequent reactions.

By studying the reaction mechanism, chemists can understand and predict the behavior of catalysts and design processes that maximize their effectiveness.

Physical States

Physical states refer to the distinct forms that different phases of matter take on, commonly known as solid, liquid, and gas. In homogeneous catalysis, the term "homogeneous" implies that the reactants and catalyst share the same physical state.

This shared state enhances the interaction between the catalyst and reactants, as they can readily mix and react.

• For instance, in a liquid-phase reaction, both catalyst and reactants dissolve, allowing for increased contact and reaction rates.
• Gas-phase homogeneous catalysis, such as in car exhaust systems, involves catalysts and gaseous reactants working together to convert harmful emissions.

Understanding the physical state context of a reaction helps in designing effective catalytic processes and predicting how changes in conditions can affect the reaction's dynamics.