LABORATORY CHEMICAL SAFETY SUMMARY: HYDROCHLORIC ACID AND HYDROGEN CHLORIDE

Substance

Hydrochloric acid

(Muriatic acid)

CAS 7647-01-0

Hydrogen chloride

CAS 7647-01-0

Formula

Reagent grade conc HCl contains 37 wt

% HCl in water; constant-boiling acid

(an azeotrope with water) contains ~20% HCl

HCl

Physical Properties

Concentrated acid evolves HCl at 60 °C leading to the formation of an azeotrope of constant composition

(20% HCl)

bp 110 °C, mp -24 °C

Miscible with water

bp -85 °C, mp -114 °C

Miscible with water

Odor

Sharp, irritating odor detectable at 0.25 to 10 ppm

Sharp, irritating odor detectable at 0.25 to 10 ppm

Vapor Density

 

1.27 (air = 1.0)

Toxicity Data

LD50 oral (rabbit)

900 mg/kg

 

LC50 inhal (rat)

3124 ppm (1 h)

 

PEL (OSHA)

5 ppm (7 mg/m3; ceiling)

 

TLV (ACGIH)

5 ppm (7.5 mg/m3; ceiling)

Major Hazards

Highly corrosive; causes severe burns on eye and skin contact and upon inhalation of gas.

Toxicity

Hydrochloric acid and hydrogen chloride gas are highly corrosive substances that may cause severe burns upon contact with any body tissue. The aqueous acid and gas are strong eye irritants and lacrimators. Contact of conc hydrochloric acid or concentrated HCl vapor with the eyes may cause severe injury, resulting in permanent impairment of vision and possible blindness, and skin contact results in severe burns. Ingestion can cause severe burns of the mouth, throat, and gastrointestinal system and can be fatal. Inhalation of hydrogen chloride gas can cause severe irritation and injury to the upper respiratory tract and lungs, and exposure to high concentrations may cause death. HCl gas is regarded as having adequate warning properties.

Hydrogen chloride has not been found to be carcinogenic or to show reproductive or developmental toxicity in humans.

Flammability and Explosibility

Noncombustible, but contact with metals may produce highly flammable hydrogen gas.



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