Hydrochloric Acid SDS: Lab Safety & GHS Guide

Q: What is the chemical formula and CAS number on a hydrochloric acid SDS?

On Section 1 and 3 of an SDS, the chemical formula is HCl and the registry number is CAS 7647-01-0. Aqueous solutions represent dissolved hydrogen chloride gas, transported under UN number UN 1789.

Q: What are the primary exposure limits for hydrochloric acid in the workplace?

Under OSHA 29 CFR 1910.1000 Table Z-1, the Permissible Exposure Limit (PEL) for hydrogen chloride is a Ceiling of 5 ppm (7 mg/m³). NIOSH also establishes a Ceiling REL of 5 ppm and an IDLH value of 50 ppm.

Q: How does the SDS classification change between concentrated and 0.1 M hydrochloric acid?

Concentrated hydrochloric acid (≥ 25%) carries the signal word DANGER with H314 (severe skin burns) and H335 (respiratory irritation). Dilute 0.1 M solutions fall below Category 1B skin corrosion thresholds, carrying WARNING for metal corrosivity (H290) and requiring eye protection.

Q: Can hydrochloric acid and sodium hydroxide be stored in the same cabinet?

No. Hydrochloric acid is a strong mineral acid and sodium hydroxide is a strong base. Co-storing them violates OSHA chemical segregation rules, as accidental mixing causes violent exothermic neutralization, boiling, and container rupture.

Q: What first aid is required if hydrochloric acid is swallowed?

Rinse the mouth thoroughly with water, but never induce vomiting. Inducing vomiting re-exposes esophageal tissue to corrosive acid. Seek immediate emergency medical care and contact poison control.

Short answer

A hydrochloric acid safety data sheet (SDS) details chemical hazard, handling, exposure, and emergency data for aqueous hydrogen chloride (CAS 7647-01-0, formula HCl). Governed by OSHA 29 CFR 1910.1200 and GHS standards, it defines health classifications (corrosive, severe burns, eye damage, respiratory irritation), exposure limits (OSHA PEL ceiling 5 ppm), compatible PPE, and storage segregation rules.

Definition and scope

Hydrochloric acid is the aqueous solution of hydrogen chloride gas (formula HCl, CAS 7647-01-0, UN 1789). Under OSHA’s Hazard Communication Standard (29 CFR 1910.1200), aligned with GHS, chemical distributors must provide a standardized 16-section safety data sheet. Known historically as an MSDS or hydrochloric acid sds sheet, the document establishes uniform hazard classifications, physical constants, and emergency response benchmarks across laboratories.

Laboratories encounter hydrochloric acid across various grades: concentrated reagent (~37% HCl by weight, ~12 M) used in mineral digestion, intermediate dilutions (10% to 25%), and volumetric bench solutions (such as 1.0 M and 0.1M HCl SDS solutions) applied in titrations and buffer preparation. For concentrated solutions (≥ 25%), Section 2 mandates the signal word DANGER and pictograms GHS05 (Corrosion) and GHS07 (Exclamation Mark), covering hazard statements H290 (corrosive to metals), H314 (severe skin burns and eye damage), H318 (serious eye damage), and H335 (respiratory irritation).

How it works or how it is used in practice

The standardized 16-section SDS structure under OSHA 29 CFR 1910.1200 Appendix D provides an operational framework for laboratory risk management and incident response:

Section 2 (Hazard Identification): Outlines GHS statements and precautions, directing workers to avoid inhaling vapors (P260/P261) and don complete eye and skin protection (P280).
Section 4 (First-Aid Measures): Specifies acute interventions: fresh air for inhalation (P304+P340), 15-minute deluge shower for skin contact (P303+P361+P353), 15-minute eye flush (P305+P351+P338), and water rinse without induced vomiting for ingestion (P301+P330+P331). Protocols appear in corrosive chemicals lab hazards and first aid.
Section 7 and 10 (Handling and Storage): Mandates fume hood handling for concentrated acid. Prohibits co-storage with oxidizers like nitric acid, bases like sodium hydroxide, bleach, cyanides, and active metals.
Section 8 (Exposure Controls and PPE): Enforces exposure limits. The OSHA PEL (29 CFR 1910.1000 Table Z-1) and NIOSH REL set a Ceiling of 5 ppm (7 mg/m³); NIOSH sets the IDLH at 50 ppm.

For PPE, thin 4-mil to 5-mil disposable nitrile gloves provide splash protection only against concentrated 37% HCl, with rapid breakthrough. For chemical transfers, ASTM F739 permeation data requires heavy-duty (15-mil) neoprene, butyl rubber, or supported nitrile gloves with ANSI Z87.1 splash goggles and face shields. Consult nitrile gloves chemical resistance for permeation benchmarks.

Types or related concepts

Safety data sheets for hydrochloric acid vary by concentration. Under GHS Specific Concentration Limits (SCLs), hazard classifications shift across solution ranges:

Formulation and Concentration	Chemical Formula and CAS	GHS Classification and Signal Word	Hazard Statements	Handling and Storage Controls
Concentrated Reagent (35% to 38% w/w, ~12 M)	HCl (aqueous) CAS 7647-01-0	Skin Corr. 1B Eye Dam. 1 STOT SE 3 Met. Corr. 1 Signal Word: DANGER	H290, H314, H335	Fume hood mandatory; ANSI splash goggles and face shield; heavy butyl or neoprene gloves; acid cabinet.
Intermediate Dilution (10% to < 25% w/w, ~3 M to ~7 M)	HCl (aqueous) CAS 7647-01-0	Skin Irrit. 2 Eye Irrit. 2 STOT SE 3 Met. Corr. 1 Signal Word: WARNING	H290, H315, H319, H335	Fume hood recommended; splash goggles; chemical-resistant gloves; secondary containment.
Dilute Bench Reagent (0.1 M to < 1 M, ~0.36% to ~3.6% w/w)	HCl (aqueous) CAS 7647-01-0	Met. Corr. 1 Irritant (pH-dependent) Signal Word: WARNING	H290, eye/skin irritation	Ventilated room; safety goggles and nitrile gloves; avoid metallic contact.
Anhydrous Hydrogen Chloride (Compressed Gas)	HCl (pure gas) CAS 7647-01-0 UN 1050	Press. Gas Acute Tox. 3 (Inh) Skin Corr. 1A Eye Dam. 1 Signal Word: DANGER	H280, H331, H314	Gas cabinet with scrubber; ambient monitor; shut-off valves; supplied-air respirator access.

Where it matters for labs, clinics or supply decisions

Compliance with hydrochloric acid SDS requirements governs core operational practices across scientific facilities:

Storage Cabinet Construction and Incompatibility Segregation

Concentrated HCl vapors corrode standard cabinetry. Storage requires a dedicated chemical storage cabinet of polyethylene, polypropylene, or coated metal. Segregate strictly: never co-store with nitric acid (forms aqua regia, releasing nitrosyl chloride and chlorine gas), bleach (releases chlorine gas), or sodium hydroxide (exothermic heat). Consult chemical storage compatibility and segregation rules.

Spill Kit Stocking and Neutralization Protocols

Section 6 requires acid spill kits with inorganic neutralizers like sodium bicarbonate or calcium carbonate with pH indicators. Never apply concentrated sodium hydroxide due to violent splattering. See chemical spill kits and lab spill response.

Procurement and Supply Strategies

Ordering pre-diluted volumetric solutions (0.1 M or 1.0 M) eliminates hazardous 37% stock dilution, reducing acid-burn risks and simplifying hygiene plan tracking.

Common misunderstandings

Addressing common laboratory misconceptions regarding hydrochloric acid SDS mandates ensures robust risk management:

Thin disposable nitrile gloves provide complete barrier protection against concentrated acid: Standard 4-mil disposable nitrile provides splash protection only. Concentrated 37% HCl breaks through thin nitrile rapidly; splashed gloves must be replaced immediately. Stock transfers require heavy butyl or neoprene gloves.
All mineral acids share identical storage compatibility: Reducing mineral acids like hydrochloric acid must not be stored with oxidizing acids like nitric acid. Leaking vapors react to form toxic nitrosyl chloride and chlorine gas. Nitric acid requires secondary containment.
Dilute 0.1 M hydrochloric acid requires no safety precautions: Dilute 0.1 M HCl has a pH around 1.0 and remains corrosive to metals (H290). Splashes cause severe eye damage; ANSI splash goggles remain mandatory.
Water may be added directly to concentrated hydrochloric acid: Adding water to concentrated acid causes flash boiling and corrosive splattering. Always add acid slowly into water with continuous stirring.

Frequently asked questions

What is the chemical formula and CAS number on a hydrochloric acid SDS?