HYDROBROMIC ACID AND HYDROGEN BROMIDE

Hydrobromic acid Hydrogen bromide
CAS 10035-10-6 CAS 10035-10-6

Reagent grade conc HBr HBr
contains 48 wt % HBr in water

bp 126 °C, mp -11 °C bp -67 ° C, mp -87 °C
Miscible with water Miscible with water

Sharp, irritating odor Sharp, irritating odor
detectable at 2 ppm detectable at 2 ppm

2.71 (air = 1.0)

LD₅₀ oral (rabbit) 900 mg/kg

LC₅₀ inhal (rat) 2858 ppm/1 h

PEL (OSHA) 3 ppm (10 mg/m³)

TLV (ACGIH) 3 ppm (10 mg/m³; ceiling)

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.

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

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.

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 from incompatible metals. Water should never be added to HBr because splattering may result; always add acid to water. Containers of hydrobromic acid should be stored in secondary plastic trays to avoid corrosion of metal storage shelves due to drips or spills.

Hydrogen bromide gas should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C, supplemented by the procedures described in Chapter 5.H for the handling of compressed gases. Cylinders of hydrogen bromide should be stored in cool, dry locations, separated from alkali metals and other incompatible substances.

Accidents

In the event of skin contact, remove contaminated clothing and immediately wash with flowing water for at least 15 min. In case of eye contact, immediately wash with copious amounts of water for at least 15 min while holding the eyelids open. Seek medical attention. In case of ingestion, do not induce vomiting. Give large amounts of water or milk if available and transport to medical facility. In case of inhalation, remove to fresh air and seek medical attention.

Carefully neutralize spills of hydrobromic acid with a suitable agent such as powdered sodium bicarbonate, further dilute with absorbent material, place in an appropriate container, and dispose of properly. Dilution with water before applying the solid adsorbent may be an effective means of reducing exposure to hydrogen bromide vapor. Respiratory protection may be necessary in the event of a large spill or release in a confined area.

Leaks of HBr gas are evident from the formation of dense white fumes on contact with the atmosphere. Small leaks can be detected by holding an open container of concentrated ammonium hydroxide near the site of the suspected leak; dense white fumes confirm a leak is present. In case of the accidental release of hydrogen bromide gas, such as from a leaking cylinder or associated apparatus, evacuate the area and eliminate the source of the leak if this can be done safely. Remove cylinder to a fume hood or remote area if it cannot be shut off. Full respiratory protection and protective clothing may be required to deal with a hydrogen bromide release.

In many localities, hydrobromic acid or the residue from a spill may be disposed of down the drain after appropriate dilution and neutralization. Otherwise, hydrobromic acid 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. Excess hydrogen bromide in cylinders should be returned to the manufacturer.

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.