Question

On commercial scale, Nitric acid is prepared by:
(a) Haber’s process
(b) Ostwald’s process
(c) By both (a) and (b)
(d) None of these

Answer 1

Hint: Nitric acid is represented by the formula \[HN{{O}_{3}}\]. It is a very strong acid and a strong oxidizing agent. The commercial production of nitric acid starts with oxidation of ammonia.

Complete step by step answer:
Both Haber’s process and Ostwald’s process are used for the preparation of nitric acid. However, Ostwald’s process is used to prepare it commercially.
It was developed in the year 1902 by a German chemist named Wilhelm Ostwald.
This process includes following steps –
Ammonia is heated with oxygen to give nitric oxide and water
\[4N{{H}_{3}}(g)+5{{O}_{2}}(g)\to 4NO(g)+6{{H}_{2}}O(g)\]
Nitric oxide is combined with oxygen to give nitrogen dioxide
\[2NO(g)+{{O}_{2}}(g)\to 2N{{O}_{2}}(g)\]
Nitrogen dioxide is absorbed with water to produce nitric acid as an aqueous solution. This also yields nitric oxide.
\[3N{{O}_{2}}(g)+{{H}_{2}}O(l)\to 2HN{{O}_{3}}(aq)+NO(g)\]
The nitric oxide produced in step (3) is recycled and combined with oxygen and water to produce a higher concentration of nitric acid.
\[4N{{O}_{2}}(g)+{{O}_{2}}(g)+2{{H}_{2}}O(l)\to 4HN{{O}_{3}}(aq)\]
Industrial prerequisites for preparing nitric acid includes –
Pressure: 4-10 atm
Temperature: 850- 1000 degree Celsius
Pt catalyst (10% Rh content)
Therefore, the answer is – option (b) – Ostwald’s process.

Additional Information:
The commercial use of nitric acid includes – manufacture of TNT/TNG explosives, some metal nitrates (for example – silver nitrate), to produce fertilizers and many more.

Note: You must have seen in laboratories that nitric acid is generally stored in dark coloured bottles. It is because when nitric acid is exposed to sunlight or a higher temperature, it decomposes and turns yellow.