Nitric Acid

1Identification

Name

Nitric Acid

IUPAC name

nitric acid

CAS number

7697-37-2

EC number

231-714-2

Molecular formula

HNO3

Molecular weight

63.013 g/mol

InChIKey

GRYLNZFGIOXLOG-UHFFFAOYSA-N

SMILES

[N+](=O)(O)[O-]

PubChem CID

944

Synonyms

NITRIC ACID, Azotic acid, Aqua fortis, Salpetersaeure, Nital, HNO3, Acide nitrique, Acidum nitricum, Nitricum acidum, Nitrous fumes, Nitryl hydroxide, Engraver's acid, Salpetersaure, RFNA

Recommended uses

• Used primarily to produce ammonium nitrate fertilizer; also used in metal cleaning, etching, and manufacturing explosives; [ACGIH] Used as a wet etchant in semiconductor manufacturing at a standard concentration of 67%; [CSH, p. 46]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
• Acid and Alkali Cleaning of Metals [Category: Clean] Semiconductor Manufacturing [Category: Industry]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
• Enameling [Category: Hobbies] Intalagio printing [Category: Hobbies] Lithography printing [Category: Hobbies] Applying metallic patinas [Category: Hobbies]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
• Other Solvent Energy Releasers (explosives, motive propellant) Plating agent pH regulating agent Processing aids not otherwise specified Semiconductor and photovoltaic agent Soil amendments (fertilizers) Ion exchange agent Catalyst Corrosion inhibitor Not Known or Reasonably Ascertainable Cleaning agent Surface modifier Oxidizing agent Laboratory chemicals Drier Adhesion/cohesion promoter Etching agent Pigment Chelating agent Intermediate
  EPA Chemical Data Reporting (CDR)
• Other pH regulating agent Processing aids not otherwise specified Not Known or Reasonably Ascertainable Ion exchange agent Soil amendments (fertilizers) Reducing agent Dehydrating agent (desiccant) Cleaning agent Laboratory chemicals Oxidizing agent Intermediate Pigment Etching agent
  EPA Chemical Data Reporting (CDR)

Use categories: EPA Safer Chemical Functional Use Classes -> Processing Aids and Additives · Safer Chemical Classes -> Yellow triangle - The chemical has met Safer Choice Criteria for its functional ingredient-class, but has some hazard profile issues

Description

• Nitric acid, other than red fuming appears as a pale yellow to reddish brown liquid with reddish brown vapors and a suffocating odor. Very toxic by inhalation. Corrosive to metals or tissue. Accelerates the burning of combustible material and may cause ignition of combustible materials upon contact. Prolonged exposure to low concentrations or short term exposure to high concentrations may result in adverse health effects. Density 12 lb / gal.
  CAMEO Chemicals
• Nitric acid, red fuming appears as a pale yellow to reddish brown liquid generating red-brown fumes and having a suffocating odor. Very toxic by inhalation. Corrosive to metals or tissue. Prolonged exposure to low concentrations or short term exposure to high concentrations may result in adverse health effects. Rate of onset: Immediate Persistence: Hours - days Odor threshold: ~1 ppm Source/use/other hazard: Used in many industries; Very corrosive to skin/mucous membranes as well as metals & other materials.
  CAMEO Chemicals
• Nitric acid is a nitrogen oxoacid of formula HNO3 in which the nitrogen atom is bonded to a hydroxy group and by equivalent bonds to the remaining two oxygen atoms. It has a role as a reagent and a protic solvent. It is a conjugate acid of a nitrate.
  ChEBI

2Hazard identification

Signal word

Danger

Pictograms

GHS03, GHS05, GHS06

Classification source

Regulation (EC) No 1272/2008 of the European Parliament and of the Council

Precautionary statements

Other reported classifications

7 classification records exist across sources. Differences usually reflect purity, physical form or impurities.

NFPA 704 rating

• OX - Oxidizer: Materials that possess oxidizing properties.
  Occupational Safety and Health Administration (OSHA)

Health hazards

• Excerpt from ERG Guide 157 [Substances - Toxic and/or Corrosive (Non-Combustible / Water-Sensitive)]: TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance may cause severe injury, burns or death. Reaction with water or moist air may release toxic, corrosive or flammable gases. Reaction with water may generate much heat that will increase the concentration of fumes in the air. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental contamination. (ERG, 2024)
  CAMEO Chemicals
• · TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance may cause severe injury, burns or death. · Reaction with water or moist air may release toxic, corrosive or flammable gases. · Reaction with water may generate much heat that will increase the concentration of fumes in the air. · Fire will produce irritating, corrosive and/or toxic gases. · Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental contamination.
  Emergency Response Guidebook (ERG)

Fire hazards

• Excerpt from ERG Guide 157 [Substances - Toxic and/or Corrosive (Non-Combustible / Water-Sensitive)]: Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. UN1802, UN2032, UN3084, UN3093, UN1796 (above 50%), UN1826 (above 50%), and UN2031 (above 65%) may act as oxidizers. Also consult ERG Guide 140. Vapors may accumulate in confined areas (basement, tanks, hopper/tank cars, etc.). Substance may react with water (some violently), releasing corrosive and/or toxic gases and runoff. Corrosives in contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water. (ERG, 2024)
  CAMEO Chemicals
• · Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. · UN1802, UN2032, UN3084, UN3093, UN1796 (above 50%), UN1826 (above 50%), and UN2031 (above 65%) may act as oxidizers. Also consult GUIDE 140. · Vapors may accumulate in confined areas (basement, tanks, hopper/tank cars, etc.). · Substance may react with water (some violently), releasing corrosive and/or toxic gases and runoff. · Corrosives in contact with metals may evolve flammable hydrogen gas. · Containers may explode when heated or if contaminated with water.
  Emergency Response Guidebook (ERG)
• Not combustible but enhances combustion of other substances. Gives off irritating or toxic fumes (or gases) in a fire. Risk of fire and explosion on contact with incompatible substances. See Chemical Dangers.
  ILO-WHO International Chemical Safety Cards (ICSCs)

Hazards summary

• Liquid causes second or third degree burns after short contact; [CHRIS] Solutions >30% are highly corrosive to skin; Solutions <30% are corrosive; [Quick CPC] Nitrogen dioxide and nitric oxide are usually present as hazards whenever nitric acid is used. Occupational exposure may lead to acute pneumonitis and pulmonary edema. [ACGIH] May cause erosion of teeth enamel; [ICSC]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases

3Composition / information on ingredients

This page describes the pure substance. Commercial products may be solutions or mixtures. Check Section 3 of your supplier's SDS for concentrations and other ingredients.

4First-aid measures

• Excerpt from NIOSH Pocket Guide for Nitric acid: Eye: IRRIGATE IMMEDIATELY - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately. Skin: WATER FLUSH IMMEDIATELY - If this chemical contacts the skin, immediately flush the contaminated skin with water. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water. Get medical attention promptly. Breathing: RESPIRATORY SUPPORT - If a person breathes large amounts of this chemical, move the exposed person to fresh air at once.
  CAMEO Chemicals
• General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).
  Emergency Response Guidebook (ERG)
• (General first aid procedures) Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately. Skin: Water flush immediately - If this chemical contacts the skin, immediately flush the contaminated skin with water. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water. Get medical attention promptly. Breathing: Respiratory support Swallow: Medical attention immediately - If this chemical has been swallowed, get medical attention immediately.
  The National Institute for Occupational Safety and Health (NIOSH)

Symptoms of exposure

• Cough. Sore throat. Burning sensation. Shortness of breath. Laboured breathing.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• Pain. Yellow staining of the skin. Serious skin burns.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• Redness. Pain. Severe burns.
  ILO-WHO International Chemical Safety Cards (ICSCs)

5Fire-fighting measures

• Approach fire from upwind to avoid hazardous vapors & toxic decomposition products. Use flooding quantities of water as spray or fog. Use water spray to keep fire-exposed containers cool. Extinguish fire using agent suitable for surrounding fire.
  Hazardous Substances Data Bank (HSDB)
• If material /is/ involved in /a/ fire, extinguish fire using agent suitable for type of surrounding fire. (Material itself does not burn or burns with difficulty.) Use water in flooding quantities as fog. Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible.
  Hazardous Substances Data Bank (HSDB)
• If material /is/ involved in /a/ fire, use water in flooding quantities as fog. Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible. /Nitric acid, red, fuming/
  Hazardous Substances Data Bank (HSDB)

Hazardous combustion products

• May give off poisonous oxides of nitrogen & acid fumes when heated in fires.
  Hazardous Substances Data Bank (HSDB)

6Accidental release measures

Isolation and evacuation

• Excerpt from ERG Guide 157 [Substances - Toxic and/or Corrosive (Non-Combustible / Water-Sensitive)]: IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. SPILL: Increase the immediate precautionary measure distance, in the downwind direction, as necessary. FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)
  CAMEO Chemicals
• Immediate precautionary measure · Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. Spill · For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances. · For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind direction, as necessary. Fire · If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions.
  Emergency Response Guidebook (ERG)

Spill cleanup

• Evacuate danger area! Consult an expert! Personal protection: chemical protection suit including self-contained breathing apparatus. Do NOT absorb in saw-dust or other combustible absorbents. Ventilation. Collect leaking liquid in sealable containers. Cautiously neutralize remainder with sodium carbonate. Then wash away with plenty of water.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• Spilled nitric acid must not be absorbed with sawdust or other flammable material (because of the fire hazard); instead, its spread must be prevented by the construction of earth barriers.
  Hazardous Substances Data Bank (HSDB)
• 1. Ventilate area of spill or leak. 2. Flush with copious quantities of water & neutralize with alkaline material (such as soda ash, lime, etc).
  Hazardous Substances Data Bank (HSDB)
• Environmental considerations: Air spill: Apply water spray or mist to knock down vapors. Vapor knockdown water is corrosive or toxic and should be diked for containment.
  Hazardous Substances Data Bank (HSDB)

7Handling and storage

• Separated from combustible substances, reducing agents, bases, organic chemicals and food and feedstuffs. Cool. Dry. Keep in a well-ventilated room. Store only in original container.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• As a rule, nitric acid is stored in stainless steel tanks and transported in stainless steel containers.
  Hazardous Substances Data Bank (HSDB)
• Store in a cool, dry, well-ventilated location. Separate from alkalies, metals, organics, and other oxidizing materials.
  Hazardous Substances Data Bank (HSDB)
• Storage areas should be separated from other premises, well-ventilated, sheltered from sunlight and sources of heat ... should have a cement floor ... contain no substances with which ... acid might react. Large stocks ... surrounded by curbs or sills ... In the event of leakage & provisions for neutralization should be made. A fire hydrant ... should be ... outside ... storage premises. ... Electrical equipment should be of the water-proof type and resistant to acid attack. Safety lighting is desirable.
  Hazardous Substances Data Bank (HSDB)

8Exposure controls / personal protection

Personal protective equipment

• Excerpt from NIOSH Pocket Guide for Nitric acid: Skin: PREVENT SKIN CONTACT - Wear appropriate personal protective clothing to prevent skin contact. Eyes: PREVENT EYE CONTACT - Wear appropriate eye protection to prevent eye contact. Wash skin: WHEN CONTAMINATED - The worker should immediately wash the skin when it becomes contaminated. Remove: WHEN WET OR CONTAMINATED - Work clothing that becomes wet or significantly contaminated should be removed and replaced. Change: No recommendation is made specifying the need for the worker to change clothing after the workshift.
  CAMEO Chemicals
• Personnel protection: Wear appropriate chemical protective gloves, boots and goggles. Wear positive pressure self-contained breathing apparatus when fighting fires involving this material. If contact with the material /is/ anticipated, wear appropriate chemical protective clothing.
  Hazardous Substances Data Bank (HSDB)
• Air mask; Rubber acid suit, hood, boots & gloves; Chemical goggles; Safety shower & eye bath.
  Hazardous Substances Data Bank (HSDB)
• Respiratory protection at 250 mg/cu m or less: A chemical cartridge respirator with a full facepiece providing protection against nitric acid. A gas mask with a chin-style or a front- or back-mounted organic vapor canister providing protection against nitric acid. Any supplied-air respirator with a full facepiece, or helmet or hood. Any self-contained breathing apparatus with a full facepiece. A Type-C supplied-air respirator operated in pressure-demand or other positive pressure or continuous-flow mode. Respiratory protection at greater than 250 mg/cu m: Self-contained breathing apparatus with a full facepiece operated in pressure-demand or other positive pressure mode.
  Hazardous Substances Data Bank (HSDB)

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…
  The National Institute for Occupational Safety and Health (NIOSH)

9Physical and chemical properties

10Stability and reactivity

Reactivity

• 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]. Fuming nitric acid reacts with hydrogen selenide with incandescence [Berichte 3:658]. Fuming nitric acid reacts with hydrogen sulfide with incandescence [Berichte 3:658]. A mixture of finely divided magnesium and nitric acid is explosive [Pieters 1957. p. 28].
  CAMEO Chemicals
• NITRIC ACID, RED FUMING is a powerful oxidizing agent and nitrating agent. Accelerates the burning of combustible material and may cause charring and then ignition of combustible materials. May ignite alcohols, amines, ammonia, beryllium alkyls, boranes, dicyanogen, hydrazines, hydrocarbons, hydrogen, nitroalkanes, powdered metals, silanes, or thiols on contact [Bretherick 1979. p.174]. Can react violently with finely divided antimony [Pascal 10:504. 1931-34]. Reacts violently with bromine pentafluoride [Mellor 2, Supp. 1:172. 1956]. Reacts with hydrogen selenide and hydrogen sulfide with incandescence [Berichte 3:658]. Mixtures with finely divided magnesium are explosive [Pieters 1957 p.
  CAMEO Chemicals
• Fumes in air. Fully soluble in water with the release of heat. Reacts violently with water with the production of heat, fumes, and spattering.
  CAMEO Chemicals

Incompatible materials and hazardous reactions

• Reacts violently with combustible or readily oxidizable materials such as alcohols, turpentine, charcoal, organic refuse. Reacts with most metals to release hydrogen gas.
  Hazardous Substances Data Bank (HSDB)
• Can react explosively with many reducing agents.
  Hazardous Substances Data Bank (HSDB)
• Reacts explosively with metallic powders, carbides, cyanides, sulfides, alkalies, & turpentine.
  Hazardous Substances Data Bank (HSDB)

11Toxicological information

Target organs

• Eyes, skin, respiratory system, teeth
  The National Institute for Occupational Safety and Health (NIOSH)

Short-term exposure effects

• The substance is corrosive to the eyes, skin and respiratory tract. Corrosive on ingestion. Inhalation may cause asthma-like reactions (RADS). Exposure could cause asphyxiation due to swelling in the throat. Inhalation of high concentrations may cause pneumonitis and lung oedema.
  ILO-WHO International Chemical Safety Cards (ICSCs)

Long-term exposure effects

• Repeated or prolonged inhalation may cause effects on the teeth. This may result in tooth erosion. The substance may have effects on the upper respiratory tract and lungs. This may result in chronic inflammation of the respiratory tract and reduced lung function . Mists of this strong inorganic acid are carcinogenic to humans.
  ILO-WHO International Chemical Safety Cards (ICSCs)

12Ecological information

Not available in the public sources we compile. Check Section 12 of the supplier's SDS.

13Disposal considerations

• SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal and plant life; and conformance with environmental and public health regulations.
  Hazardous Substances Data Bank (HSDB)
• Disposal of waste nitric acid into sewers or watercourses should not be permitted until the ph of the soln is /SRP: adjusted/ to a range of 5.5-8.5.
  Hazardous Substances Data Bank (HSDB)
• Recovering: Sodium carbonate-calcium hydroxide is added to form the neutral soln of nitrate of sodium and calcium. This soln can be discharged after dilution with water. Also, nitric acid can be recovered and reused. Recommendable methods: Neutralization & discharge to sewer. Not recommendable method: Landfill. Peer-review: Prior to neutralization dilute 10 times. Beware - Potential toxic. (Peer-review conclusions of an IRPTC expert consultation (May 1985))
  Hazardous Substances Data Bank (HSDB)

14Transport information

UN numbers: UN 2032, UN 2031

Shipping name

• UN 2032; Nitric acid, red fuming
  Hazardous Substances Data Bank (HSDB)
• UN 2031; Nitric acid other than red fuming, with at least 65 percent, but not more than 70 percent nitric acid; Nitric acid other than red fuming, with more than 20 percent and less than 65 percent nitric acid; Nitric acid other than red fuming with not more than 20 percent nitric acid; Nitric acid other than red fuming, with more than 70 percent nitric acid
  Hazardous Substances Data Bank (HSDB)

DOT hazard class

• Nitric acid, red fuming
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172
• UN2032
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172
• Class 8 Corrosive material (49 eCFR § 173.136)
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172

DOT label

• Corrosive Oxidizer
  CAMEO Chemicals
• Corrosive Oxidizer Poison Inhalation Hazard
  CAMEO Chemicals

UN classification

• UN Hazard Class: 8; UN Subsidiary Risks: 5.1; UN Pack Group: I
  ILO-WHO International Chemical Safety Cards (ICSCs)

Emergency Response Guidebook

• 2032 157
  Emergency Response Guidebook (ERG)
• 2031 157(other than red fuming)
  The National Institute for Occupational Safety and Health (NIOSH)

How DOT hazard classes work →

15Regulatory information

• Nitric acid is designated as a hazardous substance under section 311(b)(2)(A) of the Federal Water Pollution Control Act and further regulated by the Clean Water Act Amendments of 1977 and 1978. These regulations apply to discharges of this substance. This designation includes any isomers and hydrates, as well as any solutions and mixtures containing this substance.
  Hazardous Substances Data Bank (HSDB)
• Persons in charge of vessels or facilities are required to notify the National Response Center (NRC) immediately, when there is a release of this designated hazardous substance, in an amount equal to or greater than its reportable quantity of 1000 lb or 45.4 kg. The toll free number of the NRC is (800) 424-8802. The rule for determining when notification is required is stated in 40 CFR 302.4 (section IV. D.3.b).
  Hazardous Substances Data Bank (HSDB)
• Nitric acid is an indirect food additive for use only as a component of adhesives.
  Hazardous Substances Data Bank (HSDB)

Overview of SDS regulations (OSHA HazCom, WHMIS, REACH/CLP) →

16Other information

Compiled from PubChem CID 944 and the sources it aggregates (attributed inline). Data retrieved 2026-10-12. This summary describes the pure substance and is not a supplier SDS.