• Nitric acid is a colorless liquid that is used in manufacture of inorganic and organic
nitrates and nitro compounds for fertilizers, dye intermediates, explosives, and many
different organic chemicals.
STRUCTURE, PHYSICAL AND CHEMICAL PROPERTIES OF
• It is a strong, monoprotic acid and is almost completely ionized in aqueous solution. Nitric
acid is a resonance-stabilized acid allowing it to share its electrons among its own bonds.
• Physical Properties:
• Molar mass: 63g/mol
• Color: Pure nitric acid is a colorless liquid but commercial nitric acid may be yellowish brown
due to presence of dissolved nitrogen dioxide.
• Odour: Nitric acid is a fuming, hygroscopic liquid, the fumes of which fumes gives it a choking
• Acidity: Nitric acid is a strong acid and dissociates very highly and is very corrosive.
Nitric acid dissociation’s constant is 28 (Ka value)
• Taste: It is sour in taste due to acidic in nature.
• Density: 1.513gcm-3 at 20° C. Thus pure nitric acid is about 1
times as dense as water
while commercial nitric acid has a lower density.
• Boiling point: Pure nitric acid boils at 86°C. However it undergoes partial
decomposition at this temperature.
• Melting point: When cooled below 0°C, nitric acid freezes to a white solid, which
melts at -42°C.
• Solubility: It is soluble in water in all proportions.
TYPES OF NITRIC ACID
• Fuming nitric acid:
A red liquid made by bubbling NO2 gas through concentrated HNO3.
• Concentrated nitric acid:
Its density is 1.5, containing 98% HNO3.
• Strong nitric acid:
Its density is 1.4, containing 65% HNO3.
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 and H2SO4 react to produce NaHSO4 and HNO3.
b) Brikland-Eyde’s method: By using air
c) Ostwald’s method: By ammonia
MANUFACTURING OF NITRIC ACID
• The manufacture of nitric acid is a three stage process.
• The first stage is the use of ammonia and it uses a platinum/rhodium catalyst.
STEPS IN THE PRODUCTION
• Oxidation of ammonia NH3
• Oxidation of nitric oxide
• Absorption of NO2
OSTWALD’S METHOD ;1ST STEP
• Primary oxidation (formation of nitric acid):
• Oxidation of nitric acid is carried out in 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 a catalyst.
• Chemistry of primary oxidation:
• Oxidation of ammonia is reversible and exothermic process. Therefore according to Le-Chateliars principle,
decrease in temperature favors the reaction in forward direction. In primary oxidation, 95% of ammonia is
converted to nitric oxide(NO).
• 4NH3 + 5O2 4NO + 6H2O
CONT… ;2ND STEP
• Secondary oxidation (formation of nitrogen dioxide):
Nitric oxide gas obtained by the oxidation of ammonia, is very hot. In order to reduce its
temperature, it is passed through aat exchanger where the temperature of nitric oxide is
reduce to 150°C. Nitric oxide after the cooling, is transferred to another oxidizing tower
where at about 50°C, it is oxidizing to NO2.
2NO + O2 2NO2
CONT ; 3RD STEP
Absorption of NO2 ( formation of HNO3):
• Nitrogen dioxide from secondary oxidation chamber is introduced into special absorption
• 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 obtained is very dilute. It is recycled in absorption tower so that more and more
NO2 get absorbed. HNO3 after recycle becomes about 68% concentrated.
CONT… ; 4TH STEP
• In order to increase the concentration of HNO3, vapors of HNO3 are passed over
concentrated H2SO4. Being a dehydrating agent, H2SO4 absorbs water from the HNO3 and
concentrated HNO3 is obtained.
• The important uses of nitric oxide are manufacture of various products such as:
• Explosives e.g TNT, Nitro-glycerin, Gun cotton, Ammonal
• Fertilizers such as calcium nitrate, ammonium nitrate
• Nitrate salts such as calcium nitrate, silver nitrate, ammonium nitrate
• Dyes, perfumes, Drugs
• Synthetic fibers such as Nylon
• For sulphuric acid production from nitric acid by the lead chamber process
• In purification of silver, gold, platinum
• For carving designs on copper, brass, bronze
• To make “Aqua Regia” which dissolves noble elements
PRECAUTIONS WHILE USING NITRIC ACID
• Non flammable under normal conditions but highly reactive.
• Releases toxic and irritating fumes when heated.
• Highly corrosive
• Shot term ingestion can cause burns to skin parts to digestive system
• Long term inhalation can cause the lungs diseases such as bronchitis an dcan cause tooth
INTRODUCTION TO HCL
• Hydrochloric acid is a colourless and odourless solution of hydrogen chloride and water
with chemical formula HCl.
• Once commonly referred to as muriatic acid or spirit of salt, this acid is a highly corrosive
chemical compound with several applications in industry.
• HCl is also referred as spirit of salt
• HCl is gas at room temperature
• Having pH 3.01
• Used in manufacture of organic acid
Such as use to produce PVC
• HCl as cleaning agent
Extremely powerful and is recommended as a cleaner.
• Used to neutralize
HCl use to neutrlize water in swimming pool by chemicals.
• Used to regulate pH level
• Use in activating oil wells process called oil well acidization.
• Method is use to accelerate oil production from the well.
APPLICATIONS OF HCL
• pH control and neutralization agent
Control basicity of solutions
OH- + HCl H2O + OH-
• In industry demanding purity like food pharmaceuticals drinking water.
• High quality HCl is use to control the pH of process water stream.