Nitric acid
CAS 7697-37-2



Physical Properties

Colorless, yellowish, or reddish-brown fuming liquid
"Concentrated nitric acid" (68 to 70% HNO3by wt): bp 122 �C
"White fuming nitric acid" (97.5% HNO3, 2% H2 O, <0.5% NOx): bp 83 �C, mp -42 �C
"Red fuming nitric acid" contains 85% HNO3, <5% H2 O, and 6 to 15% NOx
Miscible with water in all proportions


Suffocating fumes detectable at <5.0 ppm

Vapor Density

>1 (air = 1.0)

Vapor Pressure

57 mmHg at 25 �C for white fuming nitric acid
49 mmHg at 20 �C for 70% nitric acid

Flash Point

Not flammable

Toxicity Data

LC50 inhal (rat) 2500 ppm (1 h)

PEL (OSHA) 2 ppm (5 mg/m3)

TLV-TWA (ACGIH) 2 ppm (5.2 mg/m3)

STEL (ACGIH) 4 ppm (10 mg/m3)

Major Hazards

Highly corrosive to the eyes, skin, and mucous membranes; powerful oxidizing agent that ignites on contact or reacts explosively with many organic and inorganic substances.


Concentrated nitric acid and its vapors are highly corrosive to the eyes, skin, and mucous membranes. Dilute solutions cause mild skin irritation and hardening of the epidermis. Contact with concentrated nitric acid stains the skin yellow and produces deep painful burns. Eye contact can cause severe burns and permanent damage. Inhalation of high concentrations can lead to severe respiratory irritation and delayed effects, including pulmonary edema, which may be fatal. Ingestion of nitric acid may result in burning and corrosion of the mouth, throat, and stomach. An oral dose of 10 mL can be fatal in humans.

Tests in animals demonstrate no carcinogenic or developmental toxicity for nitric acid. Tests for mutagenic activity or for reproductive hazards have not been performed.

Flammability and Explosibility

Not a combustible substance, but a strong oxidizer. Contact with easily oxidizible materials including many organic substances may result in fires or explosions.

Reactivity and Incompatibility

Nitric acid is a powerful oxidizing agent and ignites on contact or reacts explosively with a variety of organic substances including acetic anhydride, acetone, acetonitrile, many alcohols, thiols, and amines, dichloromethane, DMSO, and certain aromatic compounds including benzene. Nitric acid also reacts violently with a wide range of inorganic substances including many bases, reducing agents, alkali metals, copper, phosphorus, and ammonia. Nitric acid corrodes steel.

Storage and Handling

Nitric acid should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C. In particular, splash goggles and rubber gloves should be worn when handling this acid, and containers of nitric acid should be stored in a well ventilated location separated from organic substances and other combustible materials.


In the event of skin contact, immediately wash with water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 min (lifting upper and lower lids occasionally) and obtain medical attention. If nitric acid is ingested, obtain medical attention immediately. If large amounts of this compound are inhaled, move the person to fresh air and seek medical attention at once.

In the event of a spill, soak up nitric acid with a spill pillow or absorbent material, place in an appropriate container, and dispose of properly. Respiratory protection may be necessary in the event of a large spill or release in a confined area.


Excess nitric acid and waste material containing this substance should be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines.

The information in this LCSS has been compiled by a committee of the National Research Council from literature sources and Material Safety Data Sheets and is believed to be accurate as of July 1994. This summary is intended for use by trained laboratory personnel in conjunction with the NRC report Prudent Practices in the Laboratory: Handling and Disposal of Chemicals. This LCSS presents a concise summary of safety information that should be adequate for most laboratory uses of the title substance, but in some cases it may be advisable to consult more comprehensive references. This information should not be used as a guide to the nonlaboratory use of this chemical.

Copyright� 1995 National Academy of Sciences. All rights reserved.

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