Nitric acid and hydrochloric acid are strong acids that are highly soluble in water. Nitric acid is produced commercially via the Ostwald process, which involves catalytic oxidation of ammonia to produce nitric oxide, which is then oxidized to nitrogen dioxide and absorbed in water to form nitric acid. Hydrochloric acid is produced via electrolysis of sodium chloride to produce chlorine, which is then combined with hydrogen to form hydrochloric acid. Both acids are colorless liquids with pungent odors that are widely used in industry, such as in fertilizer production and cleaning applications. Proper storage of the acids requires acid resistant containers and secondary containment to mitigate hazards.

2. Nitric Acid &
Hydrochloric Acid:
Represented By:

3.  Introduction:
Nitric acid is a strong monoprotic acid
and is almost completely ionized in aqueous solution.
The hydrogen (proton) attaches itself to an oxygen atom, and the
other two oxygen atoms attaches off the nitrogen atom with an
alternating bond. Nitric acid is a resonance-stabilized acid allowing it
to share its electrons among its own bonds.

4. Characteristics:
Physical properties:
 Color:
Pure nitric acid is a colorless
liquid. But commercial nitric acid
may be yellowish brown, due to
the presence of dissolved nitrogen
dioxide.
 Odour:
Nitric acid is a fuming,
hygroscopic liquid, the fumes of
which give it a choking smell.
Chemical properties:
 Molar mass:
63g/mol
 Acidity:
Nitric acid is a very strong acid
and dissociates very highly, and
is very corrosive. Nitric Acid’s
Dissociation Constant is 28 (Ka
value).

5. Cont.…
 Taste:
It is sour in taste due to acidic
nature.
 Boiling point:
Pure nitric acid boils at 86oC.
However it undergoes partial
decomposition at this
temperature.
 Solubility:
It is soluble in water in all
proportions.
 Density:
Its density is 1.513 g cm-3 at
20oC. Thus pure nitric acid is
about 1½ times as dense as
water while commercial nitric
acid has a lower density.
 Melting point:
When cooled below 0oC nitric
acid freezes to a white solid,
which melts at - 42oC.

6. Manufacturing of nitric acid :
 INDUSTRIAL PREPARATION OF NITRIC ACID
 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

7. OSTWALD'S METHOD:
 Materials used:
 - Ammonia gas
 - Water
 - Oxygen gas
 CATALYST
 Platinum
 Rhodium

8. Principle:
 The first and the important step in this process is the catalytic
oxidation of ammonia by the oxygen of the air, carried out in the
presence of platinum gauze heated to 800oc.
 Nitric oxide is formed during this process. 4NH3 (g) + 502 (g) →
4NO(g) + 6H2O(g)
 Nitric oxide is cooled then it combines with more oxygen to form
nitrogen dioxide. 2NO(g) + 02 (g) → 2NO2 (g)
 Nitrogen dioxide is now converted to HNO3 by mixing it with
water and air. 4NO2 (g) + 2H2O(l) + O2 (g) → 4HNO3 (l)

9. The process involve following
steps:
1. Converter:
NH3 is mixed with dust free air in the ratio of 1:8 by volume and the
mixture is passed through a converter made up of steel and packed with
platinum gauze catalyst. The converter is heated electrically to about
800oc where ammonia is oxidized to nitric oxide.
4NH3 (g) + 502 (g) →4NO(g) + 6H2O(g)
2. Cooling pipes:
The gases escaping from the converter are cooled to about 50oc with the
help of cooling pipes.
3. Oxidation camber:
The gases are then passed through a chamber called oxidation chamber
where more of air is mixed. Here NO is oxidized to NO2 .
2NO(g) + 02 (g) → 2NO2 (g)

10. Cont.…
4. Absorption tower:
Nitrogen dioxide is then introduced into the absorption tower. It is
packed with acid resistant stones. Water sprayed from the top
dissolves NO2 in presence of oxygen to give 60% nitric acid. The
waste gases are removed from the outlet. 4NO2 (g) + 2H2O(l) +O2
(g) → 4HNO3 (l)
5. Concentration of the acid:
Dilute HNO3 is further concentrated by distilling it under reduced
pressure in the presence of conc. H2 SO4 to get about 98% HNO3.

11. Flow sheet Diagram:

13. About it’s concentration:
 Nitric acid can be concentrated up to 68%.
 It cannot be concentrated beyond this percentage by
simply boiling because the aqueous solution of this
concentration of nitric acid forms a constant boiling
mixture at 121oC.
 However, the acid can be further concentrated by one of
the following methods:
 One method get 98% nitric acid.
 Other get 100% nitric acid.

14. Methods:
 1) By passing a mixture of
nitrogen dioxide and air
through the 68% aqueous
solution.
 This solution can be further
concentrated by distilling it
with concentrated sulphuric
acid under reduced pressure.
By this method nitric acid of
98% concentration can be
obtained.
 2) If the 98% acid is cooled
to -42oC, then pure nitric
acid of 100% concentration
crystallizes out as colorless
crystals.

15. Fuming nitric acid:
 If the solution contains more than 86% nitric acid, it is referred to
as fuming nitric acid.
 Fuming nitric acid is characterized as white fuming nitric acid
and red fuming nitric acid, depending on the amount of nitrogen
dioxide present.
 At concentrations above 95%, it tends to develop a slight yellow
color due to its tendency to adsorb water from the atmosphere
into its crystal structure.
 Pure anhydrous nitric acid (100%) is a colorless liquid with a
density of 1.522 g/cm³ which solidifies at -42 °C to form white
crystals and boils at 83 °C.

16. Reactions:
 Decomposition:
When boiling in light, even at
room temperature, there is a
partial decomposition with the
formation of nitrogen dioxide
following the reaction:
4 HNO3 → 2 H2O + 4 NO2 +
O2 (72°C)
 Redox Nature:
Nitric Acid has two properties
in redox nature. It is dependent
on how concentrated the acid
solution is. (It is a very strong
oxidant).
Nitric acid (conc.): NO3- +2H+
+e -> NO2 + H2O
Nitric acid (dilute): NO3- + 4H+
+3e -> NO + 2H2O

17. Reaction with Metal:
 With metals in general :
With cold dilute nitric acid:
Metal + Nitric Acid → Metal Sulfate + Water +
Nitric Oxide
With concentrated nitric acid (cold or hot):
Metal + Nitric Acid → Metal Sulfate + Water +
Nitrogen Di-Oxide

18. Industrial Use:
 Explosives e.g.. Trinitrotoluene (TNT), Nitro-glycerin, Gun Cotton,
Ammonal Fertilizer's such as calcium nitrate, Ammonium Nitrate.
 Nitrate Salts such as calcium nitrate, silver nitrate, ammonium nitrate
 Dyes, Perfumes, Drugs
 Synthetic fibers such as Nylon
 Can make Sulphuric acid from Nitric acid by Lead Chamber process
 Used in Purification of silver, gold, platinum
 Used for carving designs on copper, brass, bronze
 Used to make “Aqua Regia” which dissolves the noble elements (aqua
regia is
 a mixture of more than one type of acid).
 Used as a Laboratory reagent.

19. Handling and preservation:
 Store nitric acid in the original container . Dilute solutions must
be stored in acid resistant bottles. Do not store nitric acid near
materials with which it might react. Because of its wide range of
incompatible chemicals, if at all possible store nitric acid in its
own storage cabinet near floor level.
 HNO3 and others acid are store in Teflon coated plastic container.
It is stored in acid resistant bottles. It is not store near the material
which are most reactive.

20. HEALTH AND
ENVIRONMENTAL ISSUES:
 Nitric acid is a powerful oxidizing agent (accepting electrons, and
very highly electronegative) and the reactions of nitric acid with
compounds such as cyanides, carbides, and metallic powders can
be explosive.
 Reactions of nitric acid with many organic compounds, such as
turpentine, are violent and hypergolic (i.e., self-igniting).
 Concentrated nitric acid dyes human skin yellow due to a
reaction with the keratin. These yellow stains turn orange when
neutralized.
 Furthermore many reactions of Nitric acid involve the release of
various NOx gases which is causing global warming.

21.  Hydrochloric acid is a colourless and odourless solution of hydrogen
chloride and water with chemical formula HCl.
 Hydrogen chloride is a diatomic molecule, consisting of
a hydrogen atom H and a chlorine atom Cl connected by a polar
covalent bond. The chlorine atom is much more electronegative than
the hydrogen atom, which makes this bond polar. Consequently, the
molecule has a large dipole moment with a negative partial
charge (δ−) at the chlorine atom and a positive partial charge (δ+) at
the hydrogen atom. Because of its high polarity, HCl is
very soluble in water (and in other polar solvents).

22. Physical and Chemical Properties:
 Appearance:
colorless, fuming liquid
 Odor:
pungent odor
 Boiling point:
53C (127F)
 Melting point:
-74C (-101F)
 Solubility:
infinite in water with
slight
evolution of heat
 Vapor pressure:
190 mm Hg @ 25C (77F)
 Density:
1.18 (water = 1)

23. Manufacturing:
 Direct synthesis by (chloralkali process)
 Organic synthesis
 Laboratory methods

24. Direct synthesis by (chloralkali
process):
 In the chloralkali process, brine (mixture of sodium chloride and
water) solution is electrolyzed producing chlorine (Cl2), sodium
hydroxide, and hydrogen (H2):
2 NaCl + 2 H2O → Cl2 + 2 NaOH + H2
 The pure chlorine gas can be combined with hydrogen to produce
hydrogen chloride in the presence of UV light:
Cl2(g) + H2(g) → 2 HCl(g)
 As the reaction is exothermic, the installation is called an HCl
oven or HCl burner. The resulting hydrogen chloride gas is
absorbed in deionized water, resulting in chemically pure
hydrochloric acid. This reaction can give a very pure product, e.g.
for use in the food industry.

25. Organic synthesis:
 The largest production of hydrochloric acid is integrated with the
formation of chlorinated and fluorinated organic compounds, e.g.,
Teflon, Freon, and other CFCs, as well as chloroacetic acid and
PVC. In the chemical reactions, hydrogen atoms on the
hydrocarbon are replaced by chlorine atoms, where upon the
released hydrogen atom recombines with the spare atom from the
chlorine molecule, forming hydrogen chloride. Fluorination is a
subsequent chlorine-replacement reaction, producing again
hydrogen chloride:
R−H + Cl2 → R−Cl + HCl
R−Cl + HF → R−F + HCl
 The resulting hydrogen chloride gas is either reused directly or
absorbed in water, resulting in hydrochloric acid of technical or
industrial grade.

26. Laboratory methods:
 Small amounts of HCl gas for laboratory use can be generated in an HCl generator
by dehydrating hydrochloric acid with either sulfuric acid or anhydrous calcium
chloride. Alternatively, HCl can be generated by the reaction of sulfuric acid with
sodium chloride:[12]
NaCl + H2SO4 → NaHSO4 + HCl
 This reaction occurs at room temperature. Provided there is NaCl remaining in the
generator and it is heated above 200 °C, the reaction proceeds further:
NaCl + NaHSO4 → HCl + Na2SO4
 For such generators to function, the reagents should be dry.
 HCl can also be prepared by the hydrolysis of certain reactive chloride compounds
such as phosphorus chlorides, thionyl chloride (SOCl2), and acyl chlorides. For
example, cold water can be gradually dripped onto phosphorus pentachloride
(PCl5) to give HCl:
PCl5 + H2O → POCl3 + 2 HCl
 High-purity streams of the gas require lecture bottles or cylinders, both of which
can be expensive. In comparison, the use of a generator requires only apparatus
and materials commonly available in a laboratory.

28. Uses:
 Used in manufacture of organic acid
 HCl as cleaning agen
 Used to neutralize
 Used to regulate pH level

29. Handling and Storage:
 Store in a cool, dry, ventilated storage area with acid resistant floors, and
good drainage.
 XLPE tanks are recommended but HDPE, LDPE, FRP, rubber-lined steel,
and polypropylene tanks can also successfully store HCl. Total fluid
capacity can affect recommended storage tanks. Tanks should be made to
1.9 specific gravity.
 Hydrochloric acid vapors are corrosive and hazardous, as well as a
regulated emission. Ensure airtight manways and connections. Employ
fume scrubbers and/or vents for HCl vapor mitigation.
 Secondary containment measures are required for bulk quantities of
hydrochloric acid due to its chemical hazards. Engineering standards must
contain 110% of total HCl tank system volume in the event of a release.
 Store hydrochloric acid away from heat sources, direct sunlight, and
incompatible materials due to the potential for evolving vapors and
hazardous reactions. HCl is considered inherently stable without
degradation. Common HCl concentration freezing points indicate freezing
is not a general concern.