Hydrobromic acid

CAS 10035-10-6

Hydrogen bromide

CAS 10035-10-6


Reagent grade conc HBr contains 48 wt

% HBr in water


Physical Properties

bp 126 °C, mp -11 °C

Miscible with water

bp -67° C, mp -87 °C

Miscible with water


Sharp, irritating odor detectable at 2 ppm

Sharp, irritating odor detectable at 2 ppm

Vapor Density


2.71 (air = 1.0)

Toxicity Data

LD50 oral (rabbit)

900 mg/kg


LC50 inhal (rat)

2858 ppm/1 h



3 ppm (10 mg/m3)



3 ppm (10 mg/m3; ceiling)

Major Hazards

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


Hydrobromic acid and hydrogen bromide gas are highly corrosive substances that can cause severe burns upon contact with all body tissues. The aqueous acid and gas are strong eye irritants and lacrimators. Contact of concentrated hydrobromic acid or concentrated HBr vapor with the eyes may cause severe injury, resulting in permanent impairment of vision and possible blindness. Skin contact with the acid or HBr gas can produce severe burns. Ingestion can lead to severe burns of the mouth, throat, and gastrointestinal system and can be fatal. Inhalation of hydrogen bromide gas can cause extreme irritation and injury to the upper respiratory tract and lungs, and exposure to high concentrations may cause death. HBr gas is regarded as having adequate warning properties.

Hydrogen bromide 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.

Reactivity and Incompatibility

Hydrobromic acid and hydrogen bromide react violently with many metals with the generation of highly flammable hydrogen gas, which may explode. Reaction with oxidizers such as permanganates, chlorates, chlorites, and hypochlorites may produce chlorine or bromine.

Storage and Handling

Hydrobromic acid should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C. Splash goggles and rubber gloves should be worn when handling this acid, and containers of HBr should be stored in a well-ventilated location separated

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