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7697-37-2 Structure

7697-37-2 Structure

Nitric acid


Acide nitrique

[Molecular Formula]

[MDL Number]

[Molecular Weight]

[MOL File]

Chemical PropertiesBack Directory

Colourless clear liquid

Nitric acid is a colorless to light brown fuming liquid with an acrid, suffocating odor. Fuming nitric acid is a reddish fuming liquid. Fumes in moist air. Often used in an aqueous solution. Fuming nitric acid is concentrated nitric acid that contains dissolved nitrogen dioxide. Nitric acid is a solution of nitrogen dioxide, NO2, in water and so-called fuming nitric acid contains an excess of NO2 and is yellow to brownish-red in color.
[mp ]

-42 °C
[bp ]

120.5 °C(lit.)
[density ]

1.41 g/mL at 20 °C
[vapor density ]

1 (vs air)
[vapor pressure ]

8 mm Hg ( 20 °C)
[Fp ]

[storage temp. ]

[Water Solubility ]

>100 g/100 mL (20 ºC)
[Sensitive ]


Nitric acid is an important material for the production of explosives. Concentrated nitric acid, usually mixed with sulfuric acid (mixed acid), is used for nitrating organic compounds. Product Data Sheet

Nitric acid is an important starting material for the production of fertilizers and chemicals. Diluted nitric acid is used for dissolving and etching metals Product Data Sheet
[Merck ]


This heavy, clear or slightly yellowish fluid is very poisonous and causes severe burns on contact with the skin. It was made by the distillation of an alkali-metal nitrate combined with sulfuric acid. The combination of nitric and sulfuric acids was used to convert plain cotton to cellulose nitrate. Nitric acid was used in the wet plate process as an additive to ferrous sulfate developers to promote a whiter image color for ambrotypes and ferrotypes. It was also added to lower the pH of the silver bath for collodion plates. Adding acid to the silver bath made collodion plates less sensitive to light, which had the beneficial effect of reducing the occurrence non-image fog.
[CAS DataBase Reference]

7697-37-2(CAS DataBase Reference)
[NIST Chemistry Reference]

Nitric acid(7697-37-2)
[EPA Substance Registry System]

7697-37-2(EPA Substance)
Safety DataBack Directory
[Hazard Codes ]

[Risk Statements ]

R8:Contact with combustible material may cause fire.
R35:Causes severe burns.
R34:Causes burns.
R20:Harmful by inhalation.
[Safety Statements ]

S23:Do not breathe gas/fumes/vapor/spray (appropriate wording to be specified by the manufacturer) .
S26:In case of contact with eyes, rinse immediately with plenty of water and seek medical advice .
S36:Wear suitable protective clothing .
S45:In case of accident or if you feel unwell, seek medical advice immediately (show label where possible) .

UN 3264 8/PG 3
[WGK Germany ]


[F ]

[HazardClass ]

[PackingGroup ]

[HS Code ]

[Safety Profile]

Poison by inhalation. A corrosive irritant to skin, eyes, and mucous membranes. A very dangerous fire hazard and very powerful oxidizing agent. Can react explosively with many reducing agents. Wdl react with water or steam to produce heat and toxic, corrosive, and flammable vapors.When heated to decomposition it emits hghly toxic fumes of NOx. See also NITRIC ACID.
[Hazardous Substances Data]

7697-37-2(Hazardous Substances Data)
Raw materials And Preparation ProductsBack Directory
【Raw materials】

Ammonia-->Oxygen-->Magnesium oxide-->CARBON MONOXIDE-->Sodium nitrate-->Dehydrolyzing agent-->Platinum-->NITRIC OXIDE-->Magnesium nitrate-->Nitrogen Tetroxide-->Compressor-->Air blower-->Heat exchanger-->cellular membranes
【Preparation Products】

3-METHYLPYRAZINE-2-CARBOXYLIC ACID-->2-Hydroxy-5-nitronicotinic acid-->5-NITROBARBITURIC ACID-->Diethyl nitromalonate-->10-Nitroanthrone-->Lanthanum(III) nitrate hexahydrate-->5-Amino-2,4,6-triiodo-N-methylisophthalamic Acid-->LEAD (II) BORATE MONOHYDRATE-->Cadmium nitrate-->NESSLER'S REAGENT-->4-Acetamido-3-nitrobenzoic acid-->2,6-Dimethyl-3-nitropyridine-->FLAVIANIC ACID-->6-NITROPIPERONAL-->3,5-DINITRO-4-HYDROXYBENZALDEHYDE-->PYRIDINE-2-SULFONIC ACID-->1,3-Dimethyl-8-nitro-1H-purine-2,6(3H,9H)-dione ,97%-->2-NITROTHIOPHENE-4-CARBOXALDEHYDE-->3,3'-DINITROBENZOPHENONE-->2-ethyl-5-nitrobenzenamine-->Mercury iodide-->mercurous bromide-->MERCUROUS CHLORIDE-->PHENYLMERCURY NITRATE-->3-Nitrobenzonitrile-->5-Methylisoxazole-3-carboxylic acid-->2-Nitrothiophene-->2-NITROMESITYLENE-->Sodium nitrohumate-->4,5-DIPHENYLIMIDAZOLE-->2,4-Dichloro-5-nitrobenzalehyde-->5-Chloro-2-hydroxy-3-nitropyridine-->CADMIUM NITRATE TETRAHYDRATE-->hydrofining catalysts (RN series)-->Mesaconic acid-->Methyl 3-nitrobenzoate-->2-HYDROXY-3,5-DINITROPYRIDINE-->MERCUROUS NITRATE-->2-METHYL-5-NITRO-PYRIMIDINE-4,6-DIOL-->TETRANITROMETHANE
Hazard InformationBack Directory
[General Description]

Nitric acid is a colorless to yellow or red liquid sometimes fuming reddish brown vapors with a suffocating odor. NITRATING ACID, MIXTURE, (WITH > 50% NITRIC ACID)(7697-37-2) is soluble in water with release of heat. NITRATING ACID, MIXTURE, (WITH > 50% NITRIC ACID)(7697-37-2) is corrosive to metals or tissue. NITRATING ACID, MIXTURE, (WITH > 50% NITRIC ACID)(7697-37-2) will accelerate the burning of combustible materials and NITRATING ACID, MIXTURE, (WITH > 50% NITRIC ACID)(7697-37-2) may even cause ignition upon contact with combustible material. NITRATING ACID, MIXTURE, (WITH > 50% NITRIC ACID)(7697-37-2) is fully soluble in water and may react violently upon contact with water with the evolution of heat, fumes and spattering. Prolonged exposure to low concentrations or short term exposure to high concentrations may result in adverse health effects. Density 10.4 lb/gal.
[Reactivity Profile]

Nitric acid; ignites upon contact with alcohols, amines, ammonia, beryllium alkyls, boranes, dicyanogen, hydrazines, hydrocarbons, hydrogen, nitroalkanes, powdered metals, silanes, or thiols [Bretherick 1979. p.174]. The reaction of finely divided antimony and nitric acid can be violent [Pascal 10:504. 1931-34]. Bromine pentafluoride reacts violently with strong nitric acid and strong sulfuric acid [Mellor 2, Supp. 1:172. 1956]. Experiments show that mixtures of over 50% nitric acid by weight in acetic anhydride may act as detonating explosives [BCISC 42:2. 1971]. An etching agent of equal portions of acetone, nitric acid, and 75% acetic acid exploded 4 hours after NITRATING ACID, MIXTURE, (WITH > 50% NITRIC ACID) was prepared and placed in a closed bottle. This is similar to a formulation for the preparation of tetranitromethane a sensitive explosive [Chem. Eng. News 38: 56. 1960]. Phosphine is violently decomposed by concentrated nitric acid, and flame is produced. Warm fuming nitric acid, dropped in a container of phosphine gas produces an explosion [Edin. Roy. Soc. 13:88. 1835]. An explosion occurs when nitric acid is brought into contact with phosphorus trichloride [Comp. Rend. 28:86]. The reaction of sodium azide and strong nitric acid is energetic [Mellor 8, Supp 2:315. 1967]. Reacts violently with water with the production of heat, fumes, and spattering.
[Air & Water Reactions]

Fumes in air. Fully soluble in water with release of heat. Reacts violently with water with the production of heat, fumes, and spattering.
[Potential Exposure]

Nitric acid is the second most important industrial acid and its production represents the sixth largest chemical industry in the United States. Nitric acid is used in chemicals, explosives, fertilizers, steel pickling; metal cleaning. The largest use of nitric acid is in the production of fertilizers. Almost 15% of the production goes into the manufacture of explosives, with the remaining 10% distributed among a variety of uses, such as etching, bright-dipping; electroplating, photoengraving, production of rocket fuel; and pesticide manufacture.
[First aid]

If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. If victim is conscious, administer water, or milk. Do not induce vomiting. Medical observation is recommended for 24 48 hours after breathing overexposure, as pulmonary edema may be delayed. As first aid for pneumonitis or pulmonary edema, a doctor or authorized paramedic may consider administering a drug or other inhalation therapy.
[Fire Hazard]

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Vapors may accumulate in confined areas (basement, tanks, hopper/tank cars etc.). Substance will react with water (some violently), releasing corrosive and/or toxic gases and runoff. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water.

UN2031 Nitric acid other than red fuming, with .70% nitric acid or Nitric acid other than red fuming, with at least 65%, but not >70% nitric acid, Hazard Class: 8; Labels: 8-Corrosive material, 5.1-Oxidizer. UN2032 Nitric acid, red fuming, Hazard Class: 8; Labels: 8-Corrosive material, 5.1-Oxidizer, 6.1-Poisonous material. Inhalation, Hazard Zone B. UN2031 Nitric acid other than red fuming, with >20% and <65% nitric acid or Nitric acid other than red fuming, with not >20% nitric acid, Hazard Class: 8; Labels: 8-Corrosive material.

A strong oxidizer and strong acid. Reacts violently with combustible and reducing agents; carbides, hydrogen sulfide, turpentine, charcoal, alcohol, powdered metals; strong bases. Heat causes decomposition producing nitrogen oxides. Attacks some plastics. Corrosive to metals.
[Waste Disposal]

Soda ash-slaked lime is added to form the neutral solution of nitrate of sodium and calcium. This solution can be discharged after dilution with water. Also, nitric acid can be recovered and reused in some cases as with acrylic fiber spin solutions. Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal.
Material Safety Data Sheet(MSDS)Back Directory
[msds information]

nitric acid(7697-37-2).msds
Questions and Answers (Q&A)Back Directory
[Physical properties]

Colorless liquid; highly corrosive; refractive index 1.397 at 16.5°C; density 1.503 g/L; freezes at –42°C; boils at 83°C; completely miscible with water; forms a constant boiling azeotrope with water at 68.8 wt% nitric acid; the azeotrope has density 1.41 g/mL and boils at 121°C.

Nitric acid was known to alchemists in ancient times. Cavendish in 1784 synthesized the acid by applying an electric spark to humid air. Earlier in 1776, Lavoisier determined that the acid contained oxygen. In 1798, Milner prepared nitric acid from ammonia along with nitrogen oxides by oxidation of ammonia vapor over red-hot manganese dioxide. In 1816, Gay-Lussac and Berthollet established its composition.
Nitric acid is one of the most important industrial chemicals in the world. Its largest use is in the fertilizer industry for producing various nitrate fertilizers. Such fertilizers include ammonium-, sodium-, potassium-, and calcium nitrates. Other major applications of nitric acid are in making nitrates and nitrooganics for use in explosives, gunpowder, and fireworks. Ammonium nitrate, nitroglycerine, nitrocellulose, and trinitrotoluenes are examples of such explosives, while barium and strontium nitrates are used in fireworks. NITRIC ACID 635Another major application is in producing cyclohexanone, a raw material for adipic acid and caprolactam to produce nylon.
Nitric acid is a common laboratory reagent. It also is one of the most used oxidizing agents, applied in several organic and inorganic syntheses. Some synthetic applications of nitric acid include the production of diazo dyes, varnishes, lacquers, plastics, polyurethanes, and detergents. Other applications are in metal etching, ore extractions, pickling of stainless steel, rocket propellant, for processing nuclear fuel, as a solvent in aqua regia, for sample digestion in metal analysis by AA or ICP, and in preparing analytical standards.
Concentrated nitric acid used in commerce is not 100% pure nitric acid. It is the constant boiling mixture containing 68% pure acid.
[Production Methods]

Nitric acid may be produced by several methods. In the laboratory, it is prepared by distilling a solution of potassium nitrate in concentrated sulfuric acid containing equal amounts (by weight) of each.
KNO3 + H2SO4 → KHSO4 + HNO3
Nitric acid decomposes to nitrogen dioxide. Therefore, the temperature must be kept as low as possible. During this preparation, nitric acid condenses as a fuming liquid. The pure acid may be obtained when it is collected at –42°C, its freezing point. When nitric acid is collected by condensation at room temperature, it may decompose partially to nitrogen pentaoxide, N2O5, which fumes in moist air. Early commercial processes were based on reaction of Chile saltpeter (NaNO3) with sulfuric acid. Concentrated nitric acid was obtained by distilling the reaction mixture.
Nitric acid also may be obtained by rapid passage of air through an electric 636 NITRIC ACIDarc. The method is based on Cavendish’s first preparation of nitric acid. In this method, nitrogen and oxygen first combine to form nitric oxide. The gaseous product mixture usually containing about 2% nitric oxide is combined with excess oxygen to form nitrogen dioxide and nitrogen pentoxide. Dissolution of these gases in water forms nitric acid. The process, however, is expensive and unsuitable for commercial application.
Currently, nitric acid is manufactured exclusively by catalytic oxidation of ammonia. Platinum or platinum-rhodium is an effective catalyst of this oxidation (Ostwald process). Three basic steps in such ammonia oxidation process are: (1) oxidation of ammonia to form nitric oxide:
4NH3 + 5O2 → 4NO + 6H2O
The above reaction is rapid and shifts almost fully to the product side. (2) oxidation of nitric oxide to form nitrogen dioxide:
2NO + O2 → 2NO2
The above reaction also is rapid and goes almost to completion below 150°C. (3) dissolution of nitrogen dioxide in water:
3NO2 + H2O → 2HNO3 + NO
This reaction is moderately exothermic, releasing 32.4 kcal/mol.
Several mechanisms have been proposed for absorption of nitrogen dioxide in water. Nitrogen dioxide readily dimerizes to tetroxide, N2O4, at low temperatures and increasing pressure.
2NO2 ↔ N2O4 ?Hrxn = –13.7 kcal/mol
Absorption of tetroxide in water also could form nitric acid and nitric oxide:
3N2O4 + 2H2O → 4HNO3 + 2NO
Several modifications in plant design and process conditions for ammonia oxidation processes have taken place in recent years. These variations are more or less based on operating pressures and temperatures, reduction of NOx emission and other environmental regulations, and the desired plant production capacity.
Nitric acid obtained in standard ammonia oxidation is usually 50 to 70% by weight aqueous solution. Pure nitric acid of 98-99% may be obtained either by extractive distillation or by direct strong nitric (DSN) processes. In the distillation method, concentrated nitric acid of 50-70% is distilled with 93% sulfuric acid in a steam-heated tower. Sulfuric acid acts as a dehydrating agent. The distilled nitric acid vapor is condensed to pure nitric acid, while sulfuric acid absorbing water from 50-70% nitric acid loses its strength to about 70% and collects at the bottom. The 70% sulfuric acid is concentrated back to 93% NITRIC ACID 637for reuse by removal of water in a sulfuric acid concentrator.
In the DSN process, nitrogen tetroxide, N2O4 obtained from ammonia oxidation is absorbed by concentrated nitric acid in the presence of air or oxygen to yield pure nitric acid. Alternatively, N2O4 may be separated from the product gases of the ammonia oxidation process by refrigeration and then is treated with dilute nitric acid in air or oxygen.

Because it is a strong oxidizing agent, nitric acid may undergo violent reactions with powerful reducing agents. Many nitration reactions of organics yield explosive products. Pure nitric acid is highly corrosive to skin causing severe injury. Concentrated acid (68.8 wt %) is moderately corrosive to skin. The acid may decompose under heating or photochemically, liberating toxic nitrogen dioxide gas.
Questions And Answer(Q&A)Back Directory

Nitric acid (HNO3) is an important industrial acid used to alter or produce many products such as fertilizers and explosives. It reacts with ammonia to produce ammonium nitrate, an important commercial chemical.
Well-known Reagent Company Product InformationBack Directory
[Acros Organics]

Nitric acid, 68-70% solution in water, for analysis ACS(7697-37-2)
[Alfa Aesar]

Nitric acid, fuming, 98%(7697-37-2)
[Sigma Aldrich]

7697-37-2 suppliers list
Tags:7697-37-2 Related Product Information
7785-23-1 59-30-3 10099-74-8 10026-22-9 7697-37-2 10042-76-9 7757-79-1 22832-87-7 7761-88-8 56-40-6 77-92-9 7631-99-4 6484-52-2 10102-43-9 7632-00-0 55896-93-0