Substance profile
Phosphorus
Phosphorus exists in three main allotropic forms: white, black, and red. It has a garlic-like odor.
01 · Identification
What Phosphorus is
Phosphorus exists in three main allotropic forms: white, black, and red. It has a garlic-like odor. Its molecular formula is P and its molecular weight is 30.974 g/mol. It boils at 280 °C, melts at 44.1 °C.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
Other names for Phosphorus
- red phosphorus
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.
03 · Physical and chemical properties
Phosphorus 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 | 280 °C (536 °F) | HSDB | |
| 280 °C (536 °F) | at 760 mmHg | CAMEO | |
| 448.28 °C (838.9 °F) | at 760 mmHg | CAMEO | |
| Melting point | 44.1 °C (111.4 °F) | HSDB | |
| 610 °C (1130 °F) | HSDB | ||
| 44 °C (111.2 °F) | CAMEO | ||
| Density | 1.83 g/cm³ | alpha-form | HSDB |
| 2.691 g/cm³ | HSDB | ||
| 2.34 g/cm³ | CAMEO | ||
| Solubility | 0.33 mg/100 g water at 15 °C; 2.7 g/100 g benzene at 15 °C; 89.8 g/100 g carbon disulfide at 10 °C | at 15 °C | HSDB |
| Vapor pressure | 0.03 mmHg | OSHA | |
| 0.026 mmHg | at 20 °C | HSDB | |
| Autoignition temperature | 260 °C (500 °F) | HSDB | |
| 400 °C (752 °F) | above this value | CAMEO | |
| Lower explosive limit (LEL) | White-yellow: Can be ignited under almost all normal temperature conditions. Red: Material that must be preheated before ignition can occur. (EPA, 1998) | CAMEO | |
| Upper explosive limit (UEL) | White-yellow: Can be ignited under almost all normal temperature conditions. Red: Material that must be preheated before ignition can occur. (EPA, 1998) | CAMEO | |
| Vapor density | 4.77 (air = 1) | HSDB | |
| Critical temperature and pressure | 721 °C (1329.8 °F) | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
04 · Source notes
Further notes on Phosphorus
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
Black: Insoluble in organic solvents; White: Insoluble in water, slightly soluble in benzene, ethanol, and chloroform, soluble in carbon disulfide; Red: Insoluble in water and organic solvents.
Source: HSDB
Solubilities in water: one part/300,000 parts water; in abs alc: one g/400 mL; in abs ether: one g/102 mL; in CHCl3: one g/40 mL; in benzene: one g/35 mL; in CS2: one g/0.8 mL. Solubility in oils: one gram phosphorus dissolves in 80 ml olive oil, 60 ml oil of turpentine, about 100 mL almond oil.
Source: HSDB
05 · Handling and storage
Storing and handling Phosphorus
Storage conditions
Separate from air, oxidizing materials, combustibles. Always keep container closed, with material under water or inert gas. /Phosphorus, white, molten/
Source: Hazardous Substances Data Bank (HSDB)
Incompatible materials
Red: Avoid uncontrolled contact with oxidizing agents ... or with strong alkaline hydroxides. Can react violently with oxidizing agent in presence of air & moisture, liberating phosphorus acids & toxic, spontaneously flammable phosphine gas.
Source: Hazardous Substances Data Bank (HSDB)
Reactivity
PHOSPHORUS, AMORPHOUS (RED OR VIOLET) is a reducing agent. Much less reactive than the allotropic white phosphorus. Reacts strongly with bromine trifluoride. [Mellor 2:113. 1946-47]. Explodes on contact with bromoazide.
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Phosphorus in the storage compatibility matrix →