Problem 89 - A Complete Resource Book in Chemistry for JEE Main

Question

Which one of the following reactions is not associated with the Solvay process of manufacture of sodium carbonate? (a) \(\mathrm{NaCl}+\mathrm{NH}_{4} \mathrm{CO}_{3} \longrightarrow \mathrm{NaHCO}_{3}+\mathrm{NH}_{4} \mathrm{Cl}\) (b) \(2 \mathrm{NaOH}+\mathrm{CO}_{2} \longrightarrow \mathrm{Na}_{2} \mathrm{CO}_{3}+\mathrm{H}_{2} \mathrm{O}\) (c) \(2 \mathrm{NaHCO}_{3} \longrightarrow \mathrm{Na}_{2} \mathrm{CO}_{3}+\mathrm{H}_{2} \mathrm{O}+\mathrm{CO}_{2}\) (d) \(\mathrm{NH}_{3}+\mathrm{H}_{2} \mathrm{CO}_{3} \longrightarrow \mathrm{NH}_{4} \mathrm{HCO}_{3}\)

Step-by-Step Solution

Answer

(b) is not associated with the Solvay process.

Step 1: Identify the Reactions in Solvay Process

The Solvay process involves several key reactions to manufacture sodium carbonate. These reactions include the formation of sodium bicarbonate from sodium chloride and ammonium bicarbonate, followed by the decomposition of sodium bicarbonate to produce sodium carbonate, carbon dioxide, and water.

Step 2: Assess Each Given Reaction

Examine each given reaction to determine whether it is part of the Solvay process:(a) \( \mathrm{NaCl} + \mathrm{NH}_4 \mathrm{CO}_3 \rightarrow \mathrm{NaHCO}_3 + \mathrm{NH}_4 \mathrm{Cl} \) - This is a part of the Solvay process where sodium bicarbonate is formed.(b) \( 2 \mathrm{NaOH} + \mathrm{CO}_2 \rightarrow \mathrm{Na}_2 \mathrm{CO}_3 + \mathrm{H}_2 \mathrm{O} \) - This is not typically part of the Solvay process; sodium hydroxide is not a reactant used.(c) \( 2 \mathrm{NaHCO}_3 \rightarrow \mathrm{Na}_2 \mathrm{CO}_3 + \mathrm{H}_2 \mathrm{O} + \mathrm{CO}_2 \) - This process breaks down sodium bicarbonate to sodium carbonate, a step that aligns with the Solvay process.(d) \( \mathrm{NH}_3 + \mathrm{H}_2 \mathrm{CO}_3 \rightarrow \mathrm{NH}_4 \mathrm{HCO}_3 \) - While not a direct Solvay process step, it aligns with reactions forming ammonium bicarbonate, a related compound in the cycle.

Step 3: Conclusion

Based on the reactions analyzed, reaction (b) is not part of the Solvay process. The involvement of sodium hydroxide and its reaction with carbon dioxide to form sodium carbonate is not a step in the methodology of the Solvay process.

Key Concepts

Sodium Carbonate Manufacture

The manufacture of sodium carbonate is primarily carried out through a method known as the Solvay Process. This process is highly favored for its cost-effectiveness and efficiency in producing high-quality sodium carbonate. But have you ever wondered why sodium carbonate is so important? It's widely used in industries such as glass manufacture, detergents, chemical synthesis, and even food production. The Solvay process itself employs a series of reactions and cycles that cleverly utilize common and inexpensive raw materials, namely, salt (sodium chloride), limestone (calcium carbonate), and ammonia, to produce sodium carbonate with minimal waste. Here's a simplified overview of the steps in the Solvay process:

• First, ammonia is absorbed in a brine solution (saltwater).
• Limestone is heated to produce carbon dioxide, which then reacts with the ammonia in the brine to form ammonium bicarbonate.
• Sodium bicarbonate precipitates out of this solution, as it's not very soluble in the saturated brine.
• The sodium bicarbonate is then filtered out and calcined (heated strongly) to form sodium carbonate, releasing water and carbon dioxide in the process.
• The carbon dioxide is recycled back to react with more ammonium solution, making the system more sustainable.

This process exemplifies a well-planned industrial process that maximizes resource use while minimizing waste production.

Chemical Reactions

Understanding chemical reactions is essential for grasping the principles behind the Solvay process. In the context of sodium carbonate manufacture, several important reactions take place. Chemical reactions in the Solvay process can be broken down as follows:

• Formation of ammonium bicarbonate: Ammonia and carbon dioxide combine in water to produce ammonium bicarbonate.
• Formation of sodium bicarbonate: Ammonium bicarbonate reacts with sodium chloride to form sodium bicarbonate and ammonium chloride.
• Decomposition of sodium bicarbonate: When heated, sodium bicarbonate breaks down into sodium carbonate, water, and carbon dioxide.

Each reaction has a specific role, ensuring that sodium carbonate is efficiently produced from simple starting materials while conserving resources such as ammonia and carbon dioxide. For students studying chemistry, these reactions highlight concepts such as solubility, precipitation, and thermal decomposition—all fundamental principles in the study of chemical reactions.

Industrial Chemistry

Industrial chemistry is the application of chemical knowledge to industrial purposes and it plays a crucial role in our everyday lives. The Solvay process is a prime example of industrial chemistry, demonstrating how chemical principles are used on a large scale to produce essential chemicals like sodium carbonate. The goals of industrial chemistry include:

• Efficiency in production: Utilizing cost-effective materials and energy-efficient processes.
• Sustainable development: Recycling materials like carbon dioxide and ammonia to minimize waste.
• Economic viability: Producing high-yield products that are economically competitive.

The design of the Solvay process reflects these principles with its clever use of cycles and byproducts. By converting readily available and inexpensive raw materials into valuable products, industrial chemistry not only supports the economy but also enhances our daily lives by supplying materials necessary for a wide range of applications. Furthermore, the advancements in industrial chemistry continue to drive innovations, promoting environmentally friendly processes while addressing the global demand for sustainable resources.