Substance profile
Hydrochloric acid
Hydrochloric acid is a colorless gas with a pungent, irritating odor.
01 · Identification
What Hydrochloric acid is
Hydrochloric acid is a colorless gas with a pungent, irritating odor. It boils at -85 °C, melts at -114 °C.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
Other names for Hydrochloric acid
- muriatic acid
- hydrogen chloride solution
- HCl
- Anhydrous Hydrochloric Acid
- Anhydrous Hydrogen Chloride
- Chlorohydric Acid
- Hydrochloric Acid (Aerosol Forms Only)
- Hydrochloric Acid Gas
- Hydrochloric Acid, Anhydrous
- Hydrochloric Acid, Trimer
- Hydrogen Chloride
- Hydrogen Chloride (Anhydrous)
- Hydrogen Chloride (Gas Only)
- Hydrogen Chloride (Hydrochloric Acid)
- Hydrogen Chloride Dimer
- hydrogen chloride
02 · GHS classification
Hazards and label elements
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
| Code | Hazard statement |
|---|---|
| H331 | Toxic if inhaled. |
| H314 | Causes severe skin burns and eye damage. |
Precautionary statements: P260, P271, P280, P301, P304, P310, P331
03 · Physical and chemical properties
Hydrochloric acid properties
Every value is shown with the conditions it was measured under and the source it came from. Where sources disagree, all values are listed rather than one being picked — the difference is usually a different form of the substance, not an error.
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | -85.05 °C (-121.1 °F) | at 760 mmHg | HSDB |
| -85 °C (-121 °F) | NIOSH | ||
| 50.56 °C (123 °F) | at 760 mmHg | CAMEO | |
| Melting point | -114.22 °C (-173.6 °F) | HSDB | |
| -114.44 °C (-174 °F) | NIOSH | ||
| -114.78 °C (-174.6 °F) | CAMEO | ||
| Density | 0.0016 g/cm³ | HSDB | |
| 0.001 g/cm³ | ICSC | ||
| 1.49 g/cm³ | at 25 °C | DOE PAC | |
| Solubility | (86 °F): 67% | at 30 °C | NIOSH |
| 67 % at 86 °F (NIOSH, 2024) | at 30 °C | CAMEO | |
| Solubility in water, g/100ml at 30 °C: 67 (moderate) | at 30 °C | ICSC | |
| Vapor pressure | 30780 mmHg | NIOSH | |
| 413.6 mmHg | CAMEO | ||
| 35420 mmHg | at 25 °C | HSDB | |
| Autoignition temperature | Not flammable (USCG, 1999) | CAMEO | |
| Lower explosive limit (LEL) | Behavior in fire: Pressurized container may explode and release toxic, irritating vapors. | HSDB | |
| Nonflammable Gas | NIOSH | ||
| Not combustible. (EPA, 1998) | CAMEO | ||
| Upper explosive limit (UEL) | Not combustible. (EPA, 1998) | CAMEO | |
| Vapor density | 1.268 (air = 1) | Air = 1.000 | HSDB |
| 1.268 (air = 1) | CAMEO | ||
| 1.27 (air = 1) | CAMEO | ||
| Odor threshold | Air: 0.77 uL/L; Odor safety class C; C= less than 50% of distracted persons perceive warning of TLV. | HSDB | |
| Odor low: 7.0 mg/cu m; Odor high: 49.0 mg/cu m; strong irritating odor; Irritating concn= 49.00 mg/cu m. | HSDB | ||
| Low threshold= 0.26 ppm. High threshold= 0.3 ppm. | HSDB | ||
| Critical temperature and pressure | 51.4 °C (124.5 °F) | HSDB | |
| Corrosivity | Corrosive | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
04 · Handling and storage
Storing and handling Hydrochloric acid
Storage conditions
Keep container tightly closed in a dry and well-ventilated place. Storage class (TRGS 510): Gases
Source: Hazardous Substances Data Bank (HSDB)
Incompatible materials
The aqueous solution is a strong acid. Corrosive fumes emitted on contact with air. Reacts violently with bases, oxidizers forming toxic chlorine gas. Reacts, often violently, with acetic anhydride, active metals, aliphatic amines, alkanolamines, alkylene oxides, aromatic amines, amides, 2-aminoethanol, ammonia, ammonium hydroxide, calcium phosphide, chlorosulfonic acid, ethylene diamine, ethyleneimine, epichlorohydrin, isocyanates, metal acetylides, oleum, organic anhydrides, perchloric acid, 3-propiolactone, uranium phosphide, sulfuric acid, vinyl acetate, vinylidene fluoride. Highly corrosive to most metals, forming flammable hydrogen gas. Attacks some plastics, rubber, and coatings.
Source: Hazardous Substances Data Bank (HSDB)
Planning storage for a mix of chemicals? Check Hydrochloric acid in the storage compatibility matrix →
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