Hydrochloric Acid

Classification

Skin corrosion Cat 1B; STOT SE Cat 3 (respiratory irritation); Corrosive to metals Cat 1

Hazard statements

• H290 May be corrosive to metals.
• H314 Causes severe skin burns and eye damage.
• H335 May cause respiratory irritation.

Key precautionary statements

• P234 Keep only in original packaging.
• P260 Do not breathe dust/fume/gas/mist/vapors/spray.
• P280 Wear protective gloves/protective clothing/eye protection/face protection.
• P301+P330+P331 IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.
• P302+P361+P354 IF ON SKIN: Take off immediately all contaminated clothing. Immediately rinse with water for several minutes.
• P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
• P305+P354+P338 IF IN EYES: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
• P316 Get emergency medical help immediately.

Limits apply to hydrogen chloride, the gas that fumes off hydrochloric acid. The OSHA PEL and NIOSH REL are both ceiling limits, so 5 ppm should not be exceeded at any time during the workday. ACGIH sets a lower 2 ppm ceiling. Cal/OSHA is notably stricter, with a 0.3 ppm 8-hour TWA and a 2 ppm ceiling. State OSHA plans may set different limits.

• Appearance: Hydrogen chloride is a colorless to slightly yellow gas, shipped as a liquefied compressed gas; hydrochloric acid is its solution in water
• Odor: Pungent, irritating
• Molecular weight: 36.5
• Boiling point: -121°F (-85°C) (hydrogen chloride gas)
• Freezing point: -174°F (-114°C) (hydrogen chloride gas)
• Flash point: Not flammable
• Explosive limits: Not flammable
• Vapor pressure: 40.5 atm (hydrogen chloride gas)
• Relative gas density: 1.27 (heavier than air)
• Water solubility: 67% at 86°F (30°C)

Inhalation

Irritates the nose, throat and larynx, causing coughing and choking. High concentrations have caused laryngeal spasm and fluid in the lungs (pulmonary edema) in animal studies.

Skin

The acid causes severe burns. Repeated contact can cause dermatitis. Contact with liquefied hydrogen chloride can cause frostbite.

Eyes

Causes severe burns and serious eye damage.

Ingestion

Corrosive to the mouth, throat and stomach. Seek medical attention immediately.

Target organs

Eyes, skin, respiratory system

Gloves

Nitrile rubber. For full contact, use gloves at least 0.4 mm thick (breakthrough time 480 minutes); for splash contact, at least 0.11 mm (breakthrough time 120 minutes), per the Sigma-Aldrich SDS for 25–50% hydrochloric acid.

Eyes and face

Tightly fitting chemical safety goggles plus a face shield (8-inch minimum). Provide an eyewash and quick drench shower.

Respiratory

Use local exhaust ventilation. Up to 50 ppm, NIOSH lists respirators with cartridges or canisters that protect against hydrogen chloride, powered air-purifying respirators, or supplied-air respirators. Above 50 ppm or at unknown levels, use a full-facepiece pressure-demand SCBA.

Clothing

Chemical-protective clothing chosen for the concentration and amount handled. Remove clothing that becomes wet or contaminated, and wash skin when contaminated.

Store in a cool, dry, well-ventilated area in tightly closed, corrosion-resistant containers kept upright. Keep away from metals and from bases.

Avoid contact with skin and eyes and avoid breathing vapor or mist. Use in a fume hood or with local exhaust ventilation. Reseal opened containers carefully to prevent leaks.

Keep away from

• Hydroxides and other alkalis
• Amines
• Copper and brass
• Zinc
• Most other metals (highly corrosive to them)

• Evacuate the area and ventilate. Responders need respiratory protection, goggles, face shield and acid-resistant protective clothing.
• Stop the leak if it is safe to do so. Keep the acid out of drains and waterways.
• Soak up with inert absorbent material.
• Place in suitable closed containers and dispose of as hazardous waste.
• For transport incidents (UN1789), refer to ERG Guide 157.

Suitable extinguishing media

• Hydrochloric acid does not burn; use media suited to the surrounding fire
• Water spray
• Alcohol-resistant foam
• Dry chemical
• Carbon dioxide (CO2)

Special hazards

Heat releases hydrogen chloride gas, which is toxic and corrosive. The acid is corrosive to metals. Firefighters should wear SCBA.

• OSHA Hazard Communication (29 CFR 1910.1200): Hazardous chemical; SDS, labels and training required.
• OSHA Air Contaminants (29 CFR 1910.1000 Table Z-1): Hydrogen chloride, 5 ppm (7 mg/m³) ceiling.
• EPA CERCLA (40 CFR 302.4): Hazardous substance, reportable quantity 5,000 lb.
• EPA EPCRA Section 302 (40 CFR 355): Hydrogen chloride (gas only) is an extremely hazardous substance, threshold planning quantity 500 lb; release reportable quantity 5,000 lb.
• EPA EPCRA Section 313 (TRI) (40 CFR 372.65): Listed for acid aerosols only (mists, vapors, gas, fog and other airborne forms).
• EPA Clean Air Act 112(r) (40 CFR 68.130): Hydrochloric acid at 37% or greater, threshold quantity 15,000 lb; anhydrous hydrogen chloride, 5,000 lb.
• DOT (49 CFR 172.101): UN1789, Hydrochloric acid, Class 8, PG II for the concentrated product (per supplier SDS).

• NIOSH Pocket Guide to Chemical Hazards: Hydrogen chloride
• OSHA Occupational Chemical Database: Hydrogen chloride
• PubChem: Hydrochloric acid (CID 313)
• Sigma-Aldrich SDS: Hydrochloric acid
• 40 CFR 68.130, CAA 112(r) list of regulated substances