Substance profile
Chlorine
Chlorine is a yellowish-green gas with a suffocating odor.
01 · Identification
What Chlorine is
Chlorine is a yellowish-green gas with a suffocating odor. It boils at -34 °C, melts at -101 °C.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
Other names for Chlorine
- chlorine gas
- Cl2
- Bertholite
- Chlorine Mol.
- Chlorine Molecule (Cl2)
- Diatomic Chlorine
- Dichlorine
- Molecular Chlorine
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 |
|---|---|
| H270 | May cause or intensify fire; oxidiser. |
| H331 | Toxic if inhaled. |
| H335 | May cause respiratory irritation. |
| H315 | Causes skin irritation. |
| H319 | Causes serious eye irritation. |
| H400 | Very toxic to aquatic life. |
Precautionary statements: P260, P264, P271, P273, P280, P302, P304, P305, P310, P313, P332, P337, P338, P352, P391, P501
03 · Physical and chemical properties
Chlorine 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 | -34.04 °C (-29.3 °F) | HSDB | |
| -33.89 °C (-29 °F) | NIOSH | ||
| -34.61 °C (-30.3 °F) | at 760 mmHg | CAMEO | |
| Melting point | -101.5 °C (-150.7 °F) | HSDB | |
| -101.11 °C (-150 °F) | NIOSH | ||
| Density | 0.0029 g/cm³ | HSDB | |
| 1.424 g/cm³ | at 15 °C, pressurized liquid | CAMEO | |
| Solubility | 0.7% | NIOSH | |
| In water, 6,300 mg/L at 25 °C | at 25 °C | HSDB | |
| Vapor pressure | 5168 mmHg | NIOSH | |
| 5048 mmHg | at 20 °C | ICSC | |
| 5830 mmHg | at 25 °C | HSDB | |
| Autoignition temperature | Not flammable (USCG, 1999) | CAMEO | |
| Lower explosive limit (LEL) | Nonflammable Gas, but a strong oxidizer. | NIOSH | |
| Vapor density | 2.48 (air = 1) | HSDB | |
| 2.49 (air = 1) | CAMEO | ||
| 2.5 (air = 1) | ICSC | ||
| Odor threshold | Low odor threshold= 0.0300 mg/cu m. High odor threshold= 15.0000 mg/cu m. Irritating concn= 9.00 mg/cu m. | HSDB | |
| Odor Threshold Low: 0.2 [ppm] | Haz-Map | ||
| Critical temperature and pressure | 144 °C (291.2 °F) | HSDB | |
| Corrosivity | Chlorine will attack some forms of plastics, rubber, and coatings | HSDB | |
| Highly corrosive to all metals in the presence of any humidity factor | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
04 · Source notes
Further notes on Chlorine
These are descriptions rather than measured values, so they are kept out of the table above and quoted here with the source that reported them.
Solubility
Solubility in water at 25 °C with formation of aqueous Cl2 (0.062 M), HOCl (0.030 M), chloride ion (0.030 M); total solubility: 0.092 M; more soluble in alkalies
Source: HSDB
Odor
Water odor threshold: 0.0020 mg/L. Air odor threshold: 0.31 ppm. Odor Safety Class: C. C= Odor safety factor from 1-26. Less than 50% of distracted persons perceive warning of threshold limit value.
Source: HSDB
05 · Handling and storage
Storing and handling Chlorine
Storage conditions
Keep container tightly closed in a dry and well-ventilated place. Contents under pressure. Storage class (TRGS 510): Gases.
Source: Hazardous Substances Data Bank (HSDB)
Incompatible materials
Incompatible materials: Alcohols.
Source: Hazardous Substances Data Bank (HSDB)
Planning storage for a mix of chemicals? Check Chlorine in the storage compatibility matrix →
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