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1. Process flow diagram (PFD) for nitric acid production. 2. Nitric acid is a strong mineral acid. It is a mono-basic acid. It is a strong oxidizing agent and can oxidize metals and nonmetals easily. It is used in the manufacture of fertilizers, silk industry, explosive materials such as (T.N.T) etc. This is production of nitric acid manufacturing method by catalytic oxidation of ammonia (Ostwald’s Process). OSTWALD'S METHOD: MATERIALS USED: Ammonia gas Water Oxygen gas CATALYST: Platinum DETAILS OF PROCESS:
1 st STEP PRIMARY OXIDATION (formation of nitric acid) Oxidation of ammonia is carried out in a catalytic chamber in which one part of ammonia and eight parts by volume of oxygen are reacted. The temperature of chamber is about 600 o C to 800 o C. This chamber contains platinum gauze which serves as catalyst. CHEMISTRY OF PRIMARY OXIDATION: Oxidization of ammonia is a reversible and exothermic reaction. Therefore, according to Le- chatelier's principle, a decrease in temperature favours the reaction in forward direction. In primary oxidization 95% of ammonia is converted into nitric oxide (NO). 2 nd STEP SECONDARY OXIDATION (formation of nitrogen dioxide) Nitric oxide gas obtained by the oxidation of ammonia is very hot. In order to reduce its temperature, it is passed through a heat exchanger where the temperature of nitric oxide is reduced to 150 o C. Nitric oxide after cooling is transferred to another oxidizing tower where at about 50 o C it is oxidizing to NO2. 3 rd STEP ABSORPTION OF NO2 (formation of HNO3) Nitrogen dioxide from secondary oxidation chamber is introduced into a special absorption tower. NO2 gas passed through the tower and water is showered over it. By the absorption, nitric acid is obtained. 3 NO2 + H2O -> 2HNO3 + NO Nitric acid so obtained is very dilute. It is recycled in an absorption tower so that more and more NO2 get absorbed. HNO3 after recycle becomes about 50% to 70% concentrated. 4 th STEP CONCENTRATION In order to increase the concentration of HNO3, vapour of HNO3 are passed over concentrated H2SO4. Being a dehydrating agent H2SO4, absorbs water from HNO3 and concentrated HNO3 is obtained.
3. The process of producing nitric acid is a REACTIVE PROCESS . It is because, Nitric Acid is indeed what most often is referred to as called "strong acid" at the ambient temperature, and its pKa≈−1 pKa≈− 1. N itric acid in diluted solution is almost always fully dissociated except in extremely acidic solutions.

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