Which of the following reactions is a part of the large scale industrial preparation of nitric acid?
- Cu(NO3)2 + 2NO2 + 2H2O [500 K, 9 bar]Pt 4HNO3 + Cu
- NaNO3 + H2SO4 [500 K, 9 bar]Pt NaHSO4 + HNO3
- 4NH3 + 5O2 (from air) [500 K, 9 bar]Pt 4NO + 6H2O
- 4HPO3 + 2N2O5 [500 K, 9 bar]Pt 4HNO3 + P4O10
Answer
(3) 4NH3 + 5O2 (from air) [500 K, 9 bar]Pt 4NO + 6H2O
Solution
As per NCERT, on a large scale nitric acid is prepared mainly by Ostwald's process, based upon the catalytic oxidation of NH3 by atmospheric oxygen:
4NH3(g) + 5O2(g) [500 K, 9 bar]Pt/Rh gauze 4NO(g) + 6H2O(g)
2NO(g) + O2(g) 2NO2(g)
3NO2(g) + H2O(l) 2HNO3(aq) + NO(g)
⇒ Heating NaNO3 with conc. H2SO4 is the laboratory method, not the industrial one.
∴ The catalytic oxidation of ammonia is a part of the industrial preparation.
Answer: (3)