Nitric Acid (Ostwald's Process)
2nd Year Chemistry Notes
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Nitric Acid (Ostwald's Process)
Introduction
On industrial process three methods are employed for the manufacture of
nitric acid. Ostwald's Process uses Ammonia as raw material.
Ostwald's Process
When a mixture of ammonia and air is passed through a catalytic chamber
containing electrically heated Platinum Gauze, (NO) nitric oxide is
formed. This nitric oxide combines with more oxygen to form nitrogen
dioxide (NO2). This gas is then absorbed by water to form nitric acid.
The plant used in Ostwald's Process consist of following parts.
1. Catalytic Chamber
A mixture of pure and dry ammonia is passed through a catalytic chamber
containing heated (800ºC) platinum, which serves as catalyst. Here
ammonia is completely oxidized to nitric oxide.
2. Oxidation Tower
The nitric oxide is passed into oxidation tower where the temperature of
gases falls to 200ºC - 250ºC. At this temperature nitric is oxidized to
nitrogen dioxide.
2NO + O2 ----> 2NO2
3. Absorption Tower
Now the gases containing NO2 and oxygen are than sent to a series of
absorption tower, which is filled with broken quartz and water is
showered from top of the tower. Then NO2 reacts with H2O in the presence
of oxygen to form HNO3.
4NO2 + 2H2O + O2 ----> $HNO3
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2nd Year Chemistry Notes