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NITRIC ACID ( HNO3)
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INTRODUCTION
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| 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. | |||
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INDUSTRIAL
PREPARATION
OF NITRIC ACID |
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| On
industrial scale, nitric acid can be prepared by the following methods. (a) CHILLI-SALT PETER's METHOD: By NaNO3 (b) BRIKLAND-EYDE's METHOD: By using air (c) OSTWALD' s METHOD : By ammonia |
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OSTWALD'S
METHOD
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Materials
used:
Ammonia gas
Water
Oxygen gas |
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CATALYST
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| Platinum | |||
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DETAILS
OF PROCESS
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| First step | |||
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PRIMARY
OXIDATION
(formation of nitric acid) |
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| Oxidation
of ammonia is carried out in a catalyst chamber in which one part of ammonia
and eight parts of oxygen by volume are introduced.
The temperature of chamber is about 600oC. This chamber contain
a platinum gauze which serves as catalyst. For latest information , free computer courses and high impact notes visit : www.citycollegiate.com |
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CHEMISTRY
OF
PRIMARY OXIDATION |
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| Oxidization of ammonia is reversible and exothermic process. Therefore according to Le- chatelier's principle.,a decrease in temperature favour reaction in forward direction. In primary oxidization 95% of ammonia is converted into nitric oxide (NO). | |||
| Second step | |||
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SECONDARY
OXIDATION
(formation of nitrogen dioxide) |
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| Nitric oxide gas obtain 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 reduce to 150oC. Nitric oxide after cooling is transferred to another oxidizing tower where at about 50o c it is oxidizing to NO2. | |||
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| Third step | |||
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ABSORPTION
OF NO2
(formation of HNO3) |
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| 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. |
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3
NO2 + H2O
 2HNO3
+ NO |
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| Nitric acid so obtain is very dilute. It is recycled in absorption tower so that more and more NO2 get absorbed. HNO3 after recycle becomes about 68% concentrated. | |||
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| Fourth step | |||
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CONCENTRATION
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| In order to increase the concentrated of HNO3 , vapour of HNO3 are passed over concentrated H2SO4. Being a dehydrating agent H2SO4,absorbs water from HNO3 and concentrated HNO3 is obtained. | |||
| For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | |||