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The following diagram represents the industrial preparation of nitric acid from ammonia \[N{H_3} + {O_2}\] (from excess of air).
\[\mathop {N{H_3} + {O_2}}\limits_{(excess{\text{ }}air)} \xrightarrow[{(900^\circ C)}]{{(A)}}NO\xrightarrow[{Air}]{{(B)}}(C)\xrightarrow[{water}]{}HN{O_3} + NO\]
Which of the following options correctly describes the reagents, products and reaction conditions?
A.A – Catalyst and high pressure, B – Cool, C – \[N{O_2}\]
B.A – Catalyst, B – Cool, C – \[N{O_2}\]
C.A – Catalyst and high pressure, B – high pressure, C – \[N{O_2}\]
D.A –high pressure, B – Catalyst, C – \[{N_2}{O_3}\]

Answer
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Hint:
The Industrial preparation of nitric acid from ammonia is known as the Ostwald Process. During the Ostwald process the catalyst used is platinum.

Complete step by step answer:
This entire industrial production of nitric acid from ammonia can be divided into three major steps.
Step 01: ammonia is taken in presence of excess air and at a high pressure of about 4 to 10 atm and is oxidised by heating this oxygen from the air in the presence of platinum, which acts as a catalyst. This results in the formation of NO.
Step 02: the NO formed in the previous step is very hot. To reduce its temperature, it is passed through a heat exchanger and cooled. NO is again transferred to another oxidizing tower where it is cooled further and is oxidized to \[N{O_2}\]
Step 03: The Nitrogen dioxide gas that has been cooled now, is passed through a special absorption tower and water is showered over it. This results in the formation of nitric acid and NO.
Hence, going by this order of steps, we can say that –
A – Catalyst and high pressure, B – Cool, C – \[N{O_2}\].

Hence, Option A is the correct option.

Note:
Nitric acid that was produced in the last step is very dilute. The concentration is further increased by passing it repetitively through the absorption tower to remove as much NO as possible.