Ostwald's process

Ostwald's process is the manufacturing process of Nitric 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

4. PRIMARY OXIDATION: OXIDATION OF AMMONIA Oxidation of ammonia is carried out in a CATALYTIC CHAMBER Here 1 part of NH 3 and 8 parts by volume of O 2 are reacted. The temperature of chamber is about 600 o C. This chamber contains PLATINUM gauze which serves as catalyst.

5. Oxidation of NH 3 is a reversible and exothermic reaction. 4NH 3 + 5O 2 ⇄ 4NO + 6H 2 O 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).

6. Nitric oxide (NO) gas obtained by the oxidation of NH 3 is very hot. In order to reduce its temperature, it is passed through a HEAT EXCHANGER where the temperature of NO is reduced to 150 o C.

7. SECONDARY OXIDATION - FORMATION OF NO 2 NO after cooling is transferred to another oxidizing tower where at about 50 o C it is oxidized to NO 2 . 2NO + O 2 ⇄ 2NO 2

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

9. REABSORPTION OF HNO 3 Nitric acid so obtained is very dilute. It is recycled in an absorption tower so that more and more NO 2 get absorbed. HNO 3 after recycle becomes about 68% concentrated.

10. END OF LESSON