Describe Ostwald's process for the manufacture of nitric acid. Give important uses of nitric acid.

Explanation

Nitric acid is prepared commercially by the catalytic oxidation of ammonia. This process-is known as Ostwald.s process.This process involves the following steps:
i) Converter : A mixture of ammonia with dust free air in the ratio of I: I 0 is introduced into the converter. Converter is made up of steel and is packed with platinum gauze which acts as a catalyst. It is heated up to 1100 K temperature. Ammonia. gets oxidised to nitric oxide.
`4NH_(3) + 5O_(2) overset(Pt,1100K)rarr , 4NO + 6H_(2)O`
ii) Cooling pipes : Hot gases coming out of the converter are cooled through cooling pipes.
iii) Oxidation chamber : Nitric oxide is mixed with more air to form nitrogen dioxide.

iv) Absorption tower : Nitrogen dioxide formed is introduced into the absorption tower. Water is sprayed over it, then `NO_(2)` combines with water and oxygen and gives nitric acid. `2NO_(2) + H_(2)O rarr 2HNO_(3)` + NO
v) Concentration of the acid : Nitric acid formed is concentrated by distilling under reduced pressure and then by dehydrating it with concentrated `H_(2)SO_(4)` acid.