Substance profile
Sodium hydroxide
Sodium hydroxide is white, orthogonal crystals and is odorless.
01 · Identification
What Sodium hydroxide is
Sodium hydroxide is white, orthogonal crystals and is odorless. Its molecular formula is HNaO and its molecular weight is 39.997 g/mol. It boils at 1388 °C, melts at 323 °C.
Under the GHS it carries the signal word Danger. It is classed as corrosives.
Other names for Sodium hydroxide
- caustic soda
- lye
- NaOH
- Caustic Soda, Solid
- Soda Lye
- Sodium Hydrate
- Sodium Hydroxide (Lye)
- Sodium Hydroxide, Solid
- Sodium Hydroxide, Cresol, Xylenol
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 |
|---|---|
| H314 | Causes severe skin burns and eye damage. |
03 · Physical and chemical properties
Sodium hydroxide 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 | 1388 °C (2530.4 °F) | HSDB | |
| 1390 °C (2534 °F) | NIOSH | ||
| Melting point | 323 °C (613.4 °F) | HSDB | |
| 318.33 °C (605 °F) | NIOSH | ||
| 317.78 °C (604 °F) | CAMEO | ||
| Density | 2.13 g/cm³ | HSDB | |
| 1.5 g/cm³ | at 20 °C | CAMEO | |
| Solubility | 1 g dissolves in 7.2 mL absolute alcohol, 4.2 mL methanol; also soluble in glycerol | HSDB | |
| 1 g dissolves in 0.9 mL water, 0.3 mL boiling water | HSDB | ||
| 111% | NIOSH | ||
| Vapor pressure | 0 mmHg | approx | NIOSH |
| 1.82e-21 mmHg | at 25 °C | HSDB | |
| Autoignition temperature | Not flammable (USCG, 1999) | CAMEO | |
| Lower explosive limit (LEL) | Noncombustible Solid, but when in contact with water may generate sufficient heat to ignite combustible materials. | NIOSH | |
| Corrosivity | Very corrosive (caustic) to ... aluminum metal in presence of moisture | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
04 · Handling and storage
Storing and handling Sodium hydroxide
Storage conditions
CONTAINERS SHOULD BE STORED IN ROOMS WITH TRAPPED FLOOR DRAINS TOWARDS WHICH FLOORS SHOULD BE SLANTED. WHERE FLOOR DRAINS ARE NOT PROVIDED, CURBS OR DRAINED GUTTER, COVERED WITH ... GRILL, SHOULD BE CONSTRUCTED @ DOOR OPENINGS.
Source: Hazardous Substances Data Bank (HSDB)
Incompatible materials
GENERATES CONSIDERABLE HEAT WHEN ... SOLN IS MIXED WITH ACID.
Source: Hazardous Substances Data Bank (HSDB)
Planning storage for a mix of chemicals? Check Sodium hydroxide in the storage compatibility matrix →
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