Sodium, Na
Oxygen, O
Hydrogen, H
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Names | |
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IUPAC name
Sodium hydroxide[3]
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Other names
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Identifiers | |
CAS Number
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3D model (JSmol)
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ChEBI |
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ChemSpider |
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ECHA InfoCard | 100.013.805 |
EC Number |
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E number | E524 (acidity regulators, ...) |
Gmelin Reference
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68430 |
KEGG |
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MeSH | Sodium+Hydroxide |
PubChem CID
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RTECS number |
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UNII |
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UN number | 1823 (solid) 1824 (solution) |
CompTox Dashboard (EPA)
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Properties | |
Chemical formula
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NaOH |
Molar mass | 39.9971 g/mol |
Appearance | White, opaque crystals |
Odor | odorless |
Density | 2.13 g/cm3[4] |
Melting point | 323 °C (613 °F; 596 K)[4] |
Boiling point | 1,388 °C (2,530 °F; 1,661 K)[4] |
Solubility in water
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418 g/L (0 °C) 1000 g/L (25 °C)[4] 3370 g/L (100 °C) |
Solubility | soluble in glycerol, negligible in ammonia, insoluble in ether, slowly soluble in propylene glycol |
Solubility in methanol | 238 g/L |
Solubility in ethanol | <<139 g/L |
Vapor pressure | <2.4 kPa (20 °C) 0.1 kPa (700 °C) |
Acidity (pKa) | 15.7 |
Magnetic susceptibility (χ)
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−15.8·10−6 cm3/mol (aq.)[5] |
Refractive index (nD)
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1.3576 |
Structure[6] | |
Crystal structure
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Orthorhombic, oS8 |
Space group
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Cmcm, No. 63 |
Lattice constant
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a = 0.34013 nm, b = 1.1378 nm, c = 0.33984 nm
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Formula units (Z)
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4 |
Thermochemistry[7] | |
Heat capacity (C)
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59.5 J/(mol·K) |
Std molar
entropy (S⦵298) |
64.4 J/(mol·K) |
Std enthalpy of
formation (ΔfH⦵298) |
−425.8 kJ/mol |
Gibbs free energy (ΔfG⦵)
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-379.7 kJ/mol |
Hazards | |
GHS labelling: | |
Pictograms
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Signal word
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Danger |
Hazard statements
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H290, H302, H314 |
Precautionary statements
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P280, P305+P351+P338, P310 |
NFPA 704 (fire diamond) |
3
0
1
ALK
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Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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40 mg/kg (mouse, intraperitoneal)[9] 140 - 340 mg/kg (rat, oral) 1350 mg/kg (rabbit, dermal) |
LDLo (lowest published)
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500 mg/kg (rabbit, oral)[10] |
NIOSH (US health exposure limits): | |
PEL (Permissible)
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TWA 2 mg/m3[8] |
REL (Recommended)
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C 2 mg/m3[8] |
IDLH (Immediate danger)
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10 mg/m3[8] |
Safety data sheet (SDS) | External SDS |
Related compounds | |
Other anions
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Other cations
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Related compounds
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