How is nitric acid prepared from ostwald's process ?give its reaction with zinc and iron
Answers
Answer:
Ammonia is converted to nitric acid in 2 stages. It is oxidized by heating with oxygen in the presence of a catalyst such as platinum with 10% rhodium, to form nitric oxide /nitrogen(ii)oxide and water/steam. This reaction is strongly exothermic, making it a useful heat source once initiated:[3]
4 NH3 (g) + 5 O2 (g) → 4 NO (g) + 6 H2O (g) (ΔH = −905.2 kJ/mol)
Stage two encompasses two reactions and is carried out in an absorption apparatus containing water. Initially nitric oxide is oxidized again to yield nitrogen dioxide/nitrogen(iv)oxide.[3] This gas is then readily absorbed by the water, yielding the desired product (nitric acid, albeit in a dilute form), while reducing a portion of it back to nitric oxide:[3]
2 NO (g) + O2 (g) → 2 NO2 (g) (ΔH = −114 kJ/mol)
3 NO2 (g) + H2O (l) → 2 HNO3 (aq) + NO (g) (ΔH = −117 kJ/mol)
The NO is recycled, and the acid is concentrated to the required strength by distillation.
Alternatively, if the last step is carried out in air:
4 NO2 (g) + O2 (g) + 2 H2O (l) → 4 HNO3 (aq)
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