Nitric acid is produced through a two-step Ostwald process involving the oxidation of ammonia to nitric oxide followed by the absorption of nitrogen dioxide in water to form nitric acid. It is a colorless, corrosive, and toxic mineral acid that is commonly used in fertilizers and explosives due to its oxidizing properties. Some of the major producers of nitric acid in Pakistan include Ahmad Chemicals, Karakuram Scientific Company, and several fertilizer companies.

2. Nitric acid is the result of a number of chemical
reactions that produce a colorless corrosive and
toxic mineral acid which tends to have a yellow
color when stored for any length of time, due to an
accumulation of nitric oxides. It's scientific name is
HNO3. HNO3 stands for one hydrogen atom, one
nitrogen atom, and 3 oxygen atoms. Below is a
picture of what it looks like.

3. The first mention of nitric acid is in Pseudo-Geber's De
InventioneVeritatis, wherein it is obtained by calcining a
mixture of niter, alum and blue vitriol. It was again
described by Albert the Great in the 13th century and
by Ramon Lull, who prepared it by heating niter and clay
and called it "eau forte" (aqua fortis).
Glauber devised a process to obtain it by distilling
potassium nitrate with sulfuric acid. In
1776 Lavoisier showed that it contained oxygen, and in
1785 Henry Cavendish determined its precise
composition and showed that it could be synthesized by
passing a stream of electric sparks through moist air.

4. • The Ostwald process converts ammonia to nitric acid
and involves two steps.
• In step 1, ammonia is oxidized to form nitric oxide and
also nitrogen dioxide.
• Then in step 2, the nitrogen dioxide that was formed is
absorbed in water.This in-turn forms nitric acid.
• The Ostwald process has many well-known uses in
both the industrial and health field.Through the
Ostwald process, nitric acid is commonly used in
fertilizers and pharmaceuticals, and because of it’s
chemical reaction with some compounds it is used in
rocket fuel and explosives like trinitrotoluene (TNT).

6. 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
600 C.This chamber contains a platinum gauze which serves as
catalyst.
Oxidization of ammonia is reversible and exothermic process.
Therefore according to Le- chatelier’s principle, a decrease in
temperature favors reaction in forward direction. In primary
oxidization 95% of ammonia is converted into nitric oxide
(NO).
4NH3 + 5O2 ↔ 4NO + 6H2O ?H -24.8 Kcal/mol.

7. 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
reduces to 150 C.
Nitric oxide after cooling is transferred to another
oxidizing tower where at about 50 C it is oxidized to
nitrogen dioxide (NO2).
2NO + O2 ↔2 NO2

8. 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.
3NO2 + H2O -> 2HNO3 + NO
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 per cent concentrated.

9. In order to increase the
concentration of HNO3,
vapors of HNO3 are passed
over concentrated H2SO4.
Being a dehydrating agent,
H2SO4 absorbs water from
HNO3 and concentrated
HNO3 is obtained.

13. o Nitric Acid is commonly used in industry and agriculture.
o It is highly used in the manufacturing of explosives.
o It is a component of solid rocket fuels, and acts as an oxidizer.
o It is used as a chemical reagent to identify various other metals.
o Nitric acid is used In woodworking to age wood (in very diluted
forms).
o Nitric acid can be used as an inexpensive process to identify and assess
the purity of gold, particularly in low-grade alloys.
o Nitric acid in a solution of alcohol and water can be used to etch
metals.
o Nitric acid is highly used in making fertilizers because it can make
plants grow faster.

16. o Nitric acid is colorless until stored for any period of time,
then it turns a yellow color.
o Nitric acid has a pungent odor.
o Its boiling point is 181.4 F/ 83 C.
o Its melting point is -43.6 F/ -42 C.
o Nitric acids specific gravity is 1.42.
o It is completely soluble in water.
o Nitric acids odor threshold is 0.29 to 0.98 ppm.
o Nitric acids molecular weight is 63.01 g/mol
o It is corrosive and reactive.
o Nitric Acid is not flammable or combustible, but because it is
a strong oxidizer it can enhance the combustion of other
substances.
o Nitric acid is stable under recommended storage conditions.
o Because nitric acid is not combustible, it has no upper or
lower explosive limits.

17. ❑Ahmad Chemicals Karachi
❑Karakuram Scientific Company Limited Karachi
❑Lyallpur Chemical and Fertilizer Limited, Lahore and
Faislabad
❑PakArab Fertilizer Multan
❑Hazara Phosphate Fertilization Private Limited Hauripur
❑Fauji Fertilizer Limited
❑Esso Fertilizer Limited