Question

In the Ostwald’s process for the manufacturing of \[HN{O_3}\], the catalyst used is:
A. \[Fe\]
B. \[Pt\]
C. \[{V_2}{O_5}\]
D. \[Mo\]

Answer 1

Hint: Ostwald process is the most common process used for the preparation of nitric acid. It is given by a German chemist named Wilhelm Ostwald and awarded the Nobel prize for his work.

Complete step by step answer: Ostwald process is used in industrial preparation of nitric acid. The process involves the conversion of ammonia to nitric acid using oxidation of ammonia.
The whole process is divided into two steps. First is the formation of nitrous gases and second is the formation of nitric acid from these gases by water absorption.
The first step is the catalytic oxidation of ammonia in presence of platinum catalyst kept in a chamber at \[600^\circ C\]. The ammonia is converted to nitric oxide during the process.
$4N{H_3} + 5{O_2} \to 4NO + 2{H_2}O$
The nitric oxide is then cooled and oxidized to nitrogen dioxide in a separate chamber at \[50^\circ C\].
$2NO + {O_2} \to 2N{O_2}$
The \[N{O_2}\] gas is then passed through an absorption chamber which contains water. The absorption of water molecules led to the formation of nitric acid.
$3N{O_2} + 2{H_2}O \to 2HN{O_3} + NO$
The nitric acid obtained after water absorption is very dilute in nature and the concentration of nitric acid is increased by removing the water. For this the dilute \[HN{O_3}\] was redistilled with sulfuric acid.
A molecule of nitric oxide generated is recycled to the second chamber to undergo the oxidation producing nitrogen dioxide.
Thus the catalyst used in the Ostwald’s process for preparing \[HN{O_3}\], is \[Pt\].
So, the correct answer is “Option B”.

Note: Copper and nickel can also be used to carry out the catalytic oxidation. Several side reactions occur during the oxidation steps. For example the dinitrogen gas is also produced during the oxidation. The removal of this gas is important to maintain the concentration of ammonia. The reaction conditions have to be maintained properly to avoid the side reactions.