Which among the following is the popular method for manufacture of ammonia?
- (a)Ostwald's process
- (b)Haber-Bosch process
- (c)Electric furnace process
- (d)Electrolysis process
Correct — B, Haber-Bosch process. Ammonia is manufactured industrially by the Haber-Bosch process, in which nitrogen and hydrogen combine directly, N2 + 3H2 gives 2NH3, at high pressure and moderate temperature over an iron catalyst. It is the standard, most widely used route for making ammonia.
- (a)Ostwald's process — Ostwald's process makes nitric acid from ammonia; it consumes ammonia rather than manufacturing it.
- (c)Electric furnace process — The electric-arc or furnace route is associated with making nitric oxide or calcium carbide, not the bulk manufacture of ammonia.
- (d)Electrolysis process — Electrolysis is used to obtain elements such as hydrogen or reactive metals; ammonia is made by the direct synthesis of nitrogen and hydrogen, not by electrolysis.
The Haber-Bosch process is the industrial synthesis of ammonia from atmospheric nitrogen and hydrogen. Because the reaction is reversible and exothermic, it is run under carefully chosen conditions of high pressure, moderate temperature and an iron catalyst to give a workable yield.
The trap is Ostwald's process, which is closely related but does the reverse — it turns ammonia into nitric acid. Since the question asks how ammonia is made, the direct nitrogen-plus-hydrogen synthesis of Haber-Bosch is the answer.
- In the Haber-Bosch process nitrogen and hydrogen combine, N2 + 3H2 gives 2NH3, in a reversible, exothermic reaction.
- Typical conditions are roughly 200 atmospheres pressure and about 450 degrees Celsius with a finely divided iron catalyst.
- The ammonia produced feeds nitrogenous fertilisers such as urea and ammonium salts, underpinning global food supply.
- Ostwald's process then oxidises ammonia to nitric acid.
- Confusing the Haber process (makes ammonia) with Ostwald's process (makes nitric acid).
- Assuming ammonia is obtained by electrolysis.
NDA/UPSC ask which process manufactures ammonia or nitric acid, or for the conditions of the Haber-Bosch reaction — pair each process with its product.
No directly related past PYQ was found.
- practice — not a real PYQ
The catalyst used in the Haber-Bosch process for manufacturing ammonia is
- (a)platinum
- (b)iron
- (c)nickel
- (d)vanadium pentoxide
Answer(b) iron — finely divided iron is the catalyst in the Haber-Bosch synthesis of ammonia.
- practice — not a real PYQ
Ostwald's process is used for the industrial manufacture of
- (a)ammonia
- (b)nitric acid
- (c)sulphuric acid
- (d)hydrochloric acid
Answer(b) nitric acid — Ostwald's process oxidises ammonia to make nitric acid.