Nitric acid is produced through a multi-step industrial process involving the oxidation of ammonia. Ammonia is oxidized to nitric oxide at high temperatures in the presence of a platinum catalyst. The nitric oxide is then cooled and further oxidized to nitrogen dioxide, which is absorbed in water to form nitric acid. The dilute nitric acid is concentrated through reabsorption, resulting in a 68% concentrated solution used in fertilizer production, explosives, and other applications requiring a strong oxidizing acid.

1. Nitric acid
XII CHEMISTRY
MS. SIDRA JAVED

2. NITRIC ACID
Nitric acid is a strong mineral acid.
It is a monobasic 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.

3. INDUSTRIAL
PREPARATION OF
NITRIC ACID

5. PRIMARY OXIDATION: OXIDATION OF AMMONIA
Oxidation of ammonia is carried out in a CATALYTIC
CHAMBER
Here 1 part of NH3 and 8 parts by volume of O2 are
reacted.
The temperature of chamber is about 600oC.
This chamber contains PLATINUM gauze which serves
as catalyst.

6. Oxidation of NH3 is a reversible and exothermic
reaction.
4NH3 + 5O2 ⇄ 4NO + 6H2O ΔH =-24.8Kcal/mol
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).

7. Nitric oxide (NO) gas obtained by the
oxidation of NH3 is very hot.
In order to reduce its temperature, it is
passed through a HEAT EXCHANGER where
the temperature of NO is reduced to 150oC.

8. SECONDARY OXIDATION - FORMATION OF NO2
NO after cooling is transferred to another
oxidizing tower where at about 50oC it is
oxidized to NO2.
2NO + O2 ⇄ 2NO2

9. ABSORPTION - FORMATION OF HNO3
NO2 from secondary oxidation chamber is
introduced into a ABSORPTION TOWER.
NO2 gas passed through the tower and water is
showered over it.
By the absorption, nitric acid (HNO3) is obtained.
3NO2 + H2O → 2HNO3 + NO

10. REABSORPTION OF HNO3
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 68%
concentrated.

11. END OF LESSON