LABORATORY CHEMICAL SAFETY SUMMARY: SODIUM AZIDE

Substance

Sodium azide

(Hydrazoic acid, sodium salt)

CAS 26628-22-8

 

Formula

NaN3

 

Physical Properties

Colorless crystalline solid

mp >275 °C (decomposes)

Readily soluble in water (41.7 g/100 mL at 17 °C)

 

Odor

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.

Toxicity

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 CH2Cl2 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



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