Sodium hydroxide
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| Names | |
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Preferred IUPAC name
Sodium hydroxide
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Systematic IUPAC name
Sodium oxidanide
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| Other names
Caustic soda
Lye |
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| Identifiers | |
1310-73-2 
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| 3D model (Jmol) | Interactive image |
| ChEBI |
CHEBI:32145
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| ChemSpider |
14114
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| ECHA InfoCard | 100.013.805 |
| EC Number | 215-185-5 |
| E number | E524 (acidity regulators, ...) |
| 68430 | |
| KEGG |
D01169
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| MeSH | Sodium+Hydroxide |
| PubChem | 14798 |
| RTECS number | WB4900000 |
| UNII |
55X04QC32I
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| UN number | 1823 |
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| Properties | |
| NaOH | |
| Molar mass | 39.9971 g mol−1 |
| Appearance | White, waxy, opaque crystals |
| Odor | odorless |
| Density | 2.13 g/cm3 |
| Melting point | 318 °C (604 °F; 591 K) |
| Boiling point | 1,388 °C (2,530 °F; 1,661 K) |
| 418 g/L (0 °C) 1110 g/L (20 °C) 3370 g/L (100 °C) |
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| Solubility | soluble in glycerol negligible in ammonia insoluble in ether |
| Solubility in methanol | 238 g/L |
| Solubility in ethanol | <<139 g/L |
| Vapor pressure | <2.4 kPa (at 20 °C) |
| Basicity (pKb) | −0.93(NaOH(aq) = Na+ + OH–) |
| −16.0·10−6 cm3/mol | |
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Refractive index (nD)
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1.3576 |
| Thermochemistry | |
| 59.66 J/mol K | |
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Std molar
entropy (S |
64 J·mol−1·K−1 |
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Std enthalpy of
formation (ΔfH |
−427 kJ·mol−1 |
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Gibbs free energy (ΔfG˚)
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-380.7 kJ/mol |
| Hazards | |
| Safety data sheet | External MSDS |
| GHS pictograms |  |
| GHS signal word | Danger |
| H314 | |
| P280, P305+351+338, P310 | |
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EU classification (DSD)
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 C |
| R-phrases | R35 |
| S-phrases | (S1/2), S26, S37/39, S45 |
| NFPA 704 | |
| Lethal dose or concentration (LD, LC): | |
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LD50 (median dose)
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40 mg/kg (mouse, intraperitoneal) |
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LDLo (lowest published)
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500 mg/kg (rabbit, oral) |
| US health exposure limits (NIOSH): | |
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PEL (Permissible)
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TWA 2 mg/m3 |
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REL (Recommended)
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C 2 mg/m3 |
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IDLH (Immediate danger)
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10 mg/m3 |
| Related compounds | |
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Other anions
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Sodium hydrosulfide |
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Other cations
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Caesium hydroxide |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is  ?) |
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| Infobox references | |
Lye
Ascarite
White caustic
Lithium hydroxide
Potassium hydroxide
Rubidium hydroxide
Sodium hydroxide (NaOH), also known as lye and caustic soda, is an inorganic compound. It is a white solid and highly caustic metallic base and alkali of sodium which is available in pellets, flakes, granules, and as prepared solutions at different concentrations. Sodium hydroxide forms an approximately 50% (by mass) saturated solution with water.
Sodium hydroxide is soluble in water, ethanol, and methanol. This alkali is deliquescent and readily absorbs moisture and carbon dioxide in air.
Sodium hydroxide is used in many industries, mostly as a strong chemical base in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents and as a drain cleaner. Worldwide production in 2004 was approximately 60 million tonnes, while demand was 51 million tonnes.
Pure sodium hydroxide is a whitish solid, sold in pellets, flakes, and granular form, as well as in solution. It is highly soluble in water, with a lower solubility in ethanol and methanol, but is insoluble in ether and other non-polar solvents.
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Wikipedia