Ostwald’s process is the industrial process to manufacture nitric acid in bulk.
Step 1: The first step involves the oxidation of ammonia which forms nitric oxide.
4NH3(g)+5O2(g)Pt/Rh gauge catalyst−−−−−−−−−−−−−→500 K,9 bar4NO(g)+6H2O(g)
Step 2: The nitric oxide so formed, combines with oxygen to give NO2.
2NO(g)+O2(g)→2NO2(g)
Step 3: Subsequently, nitrogen dioxide is dissolved in water to produce adequate concentrations of nitric acid.
3NO2(g)+H2O(l)→2HNO3(aq)+NO(g)