Problem 33 - A Complete Resource Book in Chemistry for JEE Main

Question

\(\mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g})=\frac{\mathrm{Fe} / \mathrm{Mo}, 500^{\circ} \mathrm{C}}{\mathrm{V} 200-900 \mathrm{~atm}} 2 \mathrm{NH}_{3}+22.4\) \(\mathrm{kcal}\) formation of \(\mathrm{NH}_{3}\) by above reaction shows (a) Cyanamide process (b) Serpeck's process (c) Haber process (d) None of these

Step-by-Step Solution

Answer

The reaction is described by the Haber process.

Step 1: Analyze Reaction Conditions

The given chemical reaction involves the synthesis of ammonia (\[\mathrm{N}_{2}(\mathrm{~g}) + 3 \mathrm{H}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{NH}_{3}\]). The conditions for this reaction include the use of iron (Fe) and molybdenum (Mo) catalysts, a temperature of 500°C, and a pressure range of 200-900 atm.

Step 2: Identify Reaction Process

The reaction conditions described (Fe/Mo catalyst, high temperature, and high pressure) match the Haber process, which is an industrial method for ammonia synthesis.

Step 3: Match Conditions to Process Options

Consider the options: (a) Cyanamide process, (b) Serpeck's process, (c) Haber process, (d) None of these. The Haber process is specifically known for using high pressure and temperature with metal catalysts to synthesize ammonia.

Key Concepts

Ammonia synthesis

Ammonia synthesis is a chemical process where nitrogen from the air is combined with hydrogen to produce ammonia (\[\text{N}_2(g) + 3\text{H}_2(g) \rightarrow 2\text{NH}_3\]). This is a crucial reaction in which nitrogen gas, a major component of the atmosphere, is transformed into ammonia. Ammonia is an essential compound widely used in fertilizers and numerous chemical processes.
The process involves several critical factors:

• A high temperature, typically around 500°C, is needed to ensure that the reaction progresses at a satisfactory rate.
• High pressure ranging from 200 to 900 atm is also essential, as increased pressure shifts the equilibrium towards the production of ammonia.
• Catalysts such as iron (Fe) and molybdenum (Mo) are used to speed up the reaction rate without being consumed in the process. They provide a surface where the reactant gases can adsorb, react, and then desorb as ammonia.

Understanding these process conditions helps determine which industrial method is used for ammonia synthesis, like recognizing it as the Haber process.

Industrial chemistry

Industrial chemistry involves the large-scale production of chemicals using controlled and efficient methods. In the context of ammonia synthesis, industrial chemistry plays a pivotal role because ammonia is needed in enormous quantities for agricultural and industrial purposes.
The Haber process is a prime example of industrial chemistry in action. Developed in the early 20th century, this method revolutionized the production of ammonia worldwide. The process enables massive quantities of ammonia to be synthesized continuously by:

• Utilizing controlled high-pressure and high-temperature systems to maximize yields,
• Employing metallic catalysts to reduce energy costs and improve the efficiency of the reaction,
• Designing reactors that can withstand the harsh operating conditions needed for optimal performance.

Industrial use of the Haber process supports the global demand for fertilizers, which are essential for modern agriculture. Appreciating this contributes to an understanding of how scientific advancements drive industrial development and sustainability.

Catalysts in chemical reactions

Catalysts are substances that increase the rate of a chemical reaction without being consumed by the reaction itself. In ammonia synthesis, particularly through the Haber process, catalysts are crucial to facilitate the reaction between nitrogen and hydrogen gases.
In this process, as shown in the exercise, iron (Fe) acts as the primary catalyst, supported by minor amounts of molybdenum (Mo) to enhance its effectiveness. These metal catalysts work by:

• Providing a surface for nitrogen and hydrogen to adsorb and react more efficiently,
• Lowering the activation energy required for the reaction, thus speeding up the process considerably,
• Ensuring that the equilibrium of the reaction favors the formation of ammonia under high-pressure and high-temperature conditions.

Understanding the role of catalysts is integral to grasping how the Haber process manages to synthesize ammonia effectively. By accelerating the reaction and reducing energy expenditure, catalysts are key to achieving economically viable industrial chemical processes.