Question

The steps for the manufacture of nitric acid by Ostwald process are given. Arrange them in sequence. (a) recirculation of nitric oxide (b) addition of \(\mathrm{H}_{2} \mathrm{O}\) to nitrogen dioxide (c) oxidation of nitric oxide (d) catalytic oxidation of ammonia (a) 4321 (b) 4312 (c) 3421 (d) 3412

Short answer

Question: Arrange the following steps for the manufacture of nitric acid by Ostwald process in the correct sequence: (a) recirculation of nitric oxide, (b) addition of H2O to nitrogen dioxide, (c) oxidation of nitric oxide, (d) catalytic oxidation of ammonia. Choose the correct option: (a) 4321, (b) 4312, (c) 3421, (d) 3412. Answer: (d) 3412

Step-by-step solution

Understanding the Ostwald Process

The Ostwald process is a method for producing nitric acid (HNO3) using ammonia (NH3), water (H2O), and air. The process involves the following steps: 1. Catalytic oxidation of ammonia to form nitric oxide (NO) 2. Oxidation of nitric oxide (NO) to form nitrogen dioxide (NO2) 3. Absorption of nitrogen dioxide in water to form nitric acid (HNO3) and recirculation of nitric oxide (NO). Now, let's compare the given steps with the options provided.

Matching Correct Sequences with Provided Choices

We need to match the above sequence of steps with the provided choices (a), (b), (c), and (d). - (a) recirculation of nitric oxide corresponds to step 3 in our description. - (b) addition of H2O to nitrogen dioxide corresponds to step 3 in our description. - (c) oxidation of nitric oxide corresponds to step 2 in our description. - (d) catalytic oxidation of ammonia corresponds to step 1 in our description. Therefore, the correct sequence is 1(d), 2(c), 3(b), and 4(a).

Comparing the Sequence with the Options Given

Now we just have to match our sequence 1(d), 2(c), 3(b), and 4(a) with the given options: - (a) 4321: 4(a), 3(b), 2(c), 1(d) - Incorrect - (b) 4312: 4(a), 3(b), 1(d), 2(c) - Incorrect - (c) 3421: 3(b), 4(a), 2(c), 1(d) - Incorrect - (d) 3412: 3(b), 4(a), 1(d), 2(c) - Correct The correct sequence for the Ostwald process is given by option (d), which is 3(b), 4(a), 1(d), and 2(c).

Key concepts

Nitric Acid Production

The journey from a molecule of ammonia to a drop of nitric acid is a fascinating tale of chemical transformation, known as the Ostwald process. Nitric acid production is central to the manufacture of fertilizers and explosives, making it a cornerstone in industrial chemistry.

Beginning with ammonia, a readily available source from the Haber-Bosch process, a series of reactions involving catalytic oxidation, conversion to nitrogen dioxide, and absorption in water take place. The final product, HNO3, is not just an acid but a key player in various chemical reactions and applications. Its production is a dance of precision, where conditions such as temperature, pressure, and catalysts are fine-tuned to yield the highest efficiency and purity. To give students a smoother understanding, envision the process as a conveyor belt where each step is crucial for the delivery of the final product—nitric acid.

Catalytic Oxidation of Ammonia

Imagine a miniature world where tiny molecules of ammonia meet a catalyst and transform into something entirely different—this is the first act of the Ostwald process. The catalytic oxidation of ammonia is the initial step, and it happens on the surface of a platinum-rhodium catalyst.

At high temperatures around 850°C to 950°C, ammonia (NH3) and oxygen (O2) from the air react to form nitric oxide (NO) and water vapor. This reaction is exothermic, releasing heat energy that makes it self-sustaining once initiated. Comprehending this step is crucial, as it directly influences the efficiency of the entire process. By understanding the interaction between the catalyst and the reactants, students can appreciate the importance of surface area and temperature in catalytic reactions.

Nitric Oxide Oxidation

After the initial transformation, nitric oxide (NO) is not yet ready to become nitric acid. It requires further oxidation, and that's where the plot of this chemical story thickens. The oxidation of nitric oxide involves its reaction with more oxygen (O2) to form nitrogen dioxide (NO2).

This part of the process takes place in a specially designed tower, where temperatures and pressures are controlled to ensure maximum conversion. It's a bit like adding the perfect seasoning to a dish—the right amount of oxygen at the right temperature makes all the difference. Educators often use analogies like these to help students visualize the process and understand the delicate balance between reactants and conditions required for desired outcomes.

Nitrogen Dioxide Absorption

The grand finale of the Ostwald process occurs when nitrogen dioxide, now a reddish-brown gas, takes the plunge into water. This step is known as nitrogen dioxide absorption and is a crucial transformation that ultimately results in nitric acid (HNO3).

Scientifically speaking, NO2 is absorbed into water to form a mixture of nitric acid and nitrous acid (HNO2), which quickly decomposes to give more NO2 and NO. The nitric oxide (NO) produced is recycled back into the system, where it can once again be oxidized to NO2, demonstrating an elegant and efficient use of materials. For students, understanding this cycle is vital—it's a chemical encore where everything comes full circle, emphasizing the importance of recycling and conservation in industrial processes.