Nitric acid

Synonyms & Trade Names

Aqua fortis, Engravers acid, Hydrogen nitrate, Red fuming nitric acid, RFNA, White fuming nitric acid (WFNA)

CAS No.

7697-37-2

RTECS No.

QU5775000

DOT ID & Guide

2031 157(other than red fuming)
2032 157(fuming)

Formula

HNO₃

Conversion

1 ppm = 2.58 mg/m³

IDLH

25 ppm
See: 7697372

Exposure Limits

NIOSH REL

TWA 2 ppm (5 mg/m³) ST 4 ppm (10 mg/m³)

OSHA PEL

TWA 2 ppm (5 mg/m³) See Appendix G

Measurement Methods

NIOSH 7903;
OSHA ID165SG
See: NMAM or OSHA Methods

Physical Description

Colorless, yellow, or red, fuming liquid with an acrid, suffocating odor. [Note: Often used in an aqueous solution. Fuming nitric acid is concentrated nitric acid that contains dissolved nitrogen dioxide.]

Molecular Weight

63.0

Boiling Point

181°F

Freezing Point

-44°F

Solubility

Miscible

Vapor Pressure

48 mmHg

Ionization Potential

11.95 eV

Specific Gravity

(77°F): 1.50

Flash Point

Upper Explosive Limit

Lower Explosive Limit

Noncombustible Liquid, but increases the flammability of combustible materials.

Incompatibilities & Reactivities

Combustible materials, metallic powders, hydrogen sulfide, carbides, alcohols [Note: Reacts with water to produce heat. Corrosive to metals.]

Exposure Routes

inhalation, ingestion, skin and/or eye contact

Symptoms

irritation eyes, skin, mucous membrane; delayed pulmonary edema, pneumonitis, bronchitis; dental erosion

Target Organs

Eyes, skin, respiratory system, teeth

Personal Protection/Sanitation

(See protection codes)
Skin:Prevent skin contact
Eyes:Prevent eye contact
Wash skin:When contaminated
Remove:When wet or contaminated
Change:No recommendation
Provide:Eyewash (pH<2.5), Quick drench (pH<2.5)

First Aid

(See procedures)
Eye:Irrigate immediately
Skin:Water flush immediately
Breathing:Respiratory support
Swallow:Medical attention immediately

Respirator Recommendations

NIOSH/OSHA

Up to 25 ppm:
(APF = 25) Any supplied-air respirator operated in a continuous-flow mode*
(APF = 50) Any chemical cartridge respirator with a full facepiece and cartridge(s) providing protection against the compound of concern^¿
(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern^¿
(APF = 50) Any self-contained breathing apparatus with a full facepiece
(APF = 50) Any supplied-air respirator with a full facepiece

Emergency or planned entry into unknown concentrations or IDLH conditions:
(APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode
(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus

Escape:
(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern^¿
Any appropriate escape-type, self-contained breathing apparatus

Important additional information about respirator selection

Nitric acid

NIOSH REL

OSHA PEL

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