Sodium azide
(Hydrazoic acid, sodium salt)
CAS 26628-22-8



Physical Properties

Colorless crystalline solid
mp >275 °C (decomposes)
Readily soluble in water (41.7 g/100 mL at 17 °C)


Odorless solid

Toxicity Data

LD50 oral (rat) 27 mg/kg

LD50 skin (rabbit) 20 mg/kg

TLV-TWA (ACGIH) 0.29 mg/m3(ceiling)

Major Hazards

Highly toxic by inhalation, ingestion, or skin absorption.


The acute toxicity of sodium azide is high. Symptoms of exposure include lowered blood pressure, headache, hypothermia, and in the case of serious overexposure, convulsions and death. Ingestion of 100 to 200 mg in humans may result in headache, respiratory distress, and diarrhea. Target organs are primarily the central nervous system and brain. Sodium azide rapidly hydrolyzes in water to form hydrazoic acid, a highly toxic gas that can escape from solution, presenting a serious inhalation hazard. Symptoms of acute exposure to hydrazoic acid include eye irritation, headache, dramatic decrease in blood pressure, weakness, pulmonary edema, and collapse. Solutions of sodium azide can be absorbed through the skin.

Sodium azide has not been found to be carcinogenic in humans. Chronic, low-level exposure may cause nose irritation, episodes of falling blood pressure, dizziness, and bronchitis.

Flammability and Explosibility

Flammability hazard is low, but violent decomposition can occur when heated to 275 °C. Decomposition products include oxides of nitrogen and sodium oxide.

Reactivity and Incompatibility

Sodium azide should not be allowed to come into contact with heavy metals or their salts, because it may react to form heavy metal azides, which are notorious shock-sensitive explosives. Do not pour sodium azide solutions into a copper or lead drain. Sodium azide reacts violently with carbon disulfide, bromine, nitric acid, dimethyl sulfate, and a number of heavy metals, including copper and lead. Reaction with water and acids liberates highly toxic hydrazoic acid, which is a dangerous explosive. Sodium azide is reported to react with CH2 Cl2 in the presence of DMSO to form explosive products.

Storage and Handling

Because of its high toxicity, sodium azide should be handled in the laboratory using the "basic prudent practices" of Chapter 5.C, supplemented by the additional precautions for work with compounds of high toxicity (Chapter 5.D). In particular, work with sodium azide should be conducted in a fume hood to prevent exposure by inhalation, and appropriate impermeable gloves and splash goggles should be worn at all times to prevent skin and eye contact. Containers of sodium azide should be stored in secondary containers in a cool, dry place separated from acids.


In the event of skin contact, immediately wash with soap and 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 sodium azide 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, cover sodium azide with sand, sweep up, and place in a container for disposal. Soak up spilled solutions 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 sodium azide 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.