Question: 48: Which of the following reactions is a part of the large scale industrial preparation of nitric acid?
(1) \mathrm{NaNO}_{3}+\mathrm{H}_{2} \mathrm{SO}_{4}
\xrightarrow[500 \mathrm{~K}, 9 \text { bar }]{\mathrm{Pt}} \mathrm{NaHSO}_{4}+\mathrm{HNO}_{3}(2) 4 \mathrm{NH}_{3}+5 \mathrm{O}_{2} (from air)
\xrightarrow[500 \mathrm{~K}, 9 \text { bar }]{\mathrm{Pt}} 4 \mathrm{NO}+6 \mathrm{H}_{2} \mathrm{O}(3) 4 \mathrm{HPO}_{3}+2 \mathrm{~N}_{2} \mathrm{O}_{5}
\xrightarrow[500 \mathrm{~K}, 9 \text { bar }]{\mathrm{Pt}} 4 \mathrm{HNO}_{3}+\mathrm{P}_{4} \mathrm{O}_{10}(4) \mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}+2 \mathrm{NO}_{2}+2 \mathrm{H}_{2} \mathrm{O}
\xrightarrow[500 \mathrm{~K}, 9 \text { bar }]{\mathrm{Pt}} 4 \mathrm{HNO}_{3}+\mathrm{Cu}Answer: Option (2)
Explanation:
Nitric acid is manufactured on a large scale by the Ostwald process.
The first and most important step of the Ostwald process is the catalytic oxidation of ammonia in the presence of platinum catalyst at about 500 \mathrm{~K} and 9 \text{ bar}.
The reaction involved is:
4 \mathrm{NH}_{3}+5 \mathrm{O}_{2} \rightarrow 4 \mathrm{NO}+6 \mathrm{H}_{2} \mathrm{O}The nitric oxide formed is then further oxidized to \mathrm{NO}_{2},
which is absorbed in water to finally produce nitric acid.
Reaction (1) represents laboratory preparation of nitric acid, not industrial preparation.
Reactions (3) and (4) are not steps of the Ostwald process.
Hence, the reaction that is a part of the large scale industrial preparation
of nitric acid is given in option (2).