Potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula KOH, and is commonly called caustic potash.
| Names | |
|---|---|
| IUPAC name
Potassium hydroxide | |
| Other names
Caustic potash, Lye, Potash lye, Potassia, Potassium hydrate, KOH | |
| Identifiers | |
3D model (JSmol) |
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.013.802 |
| EC Number |
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| E number | E525 (acidity regulators, ...) |
PubChem CID |
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| RTECS number |
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| UNII | |
| UN number | 1813 |
CompTox Dashboard (EPA) |
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| Properties | |
| KOH | |
| Molar mass | 56.11 g mol−1 |
| Appearance | white solid, deliquescent |
| Odor | odorless |
| Density | 2.044 g/cm3 (20 °C) 2.12 g/cm3 (25 °C) |
| Melting point | 410 °C (770 °F; 683 K) |
| Boiling point | 1,327 °C (2,421 °F; 1,600 K) |
| 85 g/100 mL (-23.2 °C) 97 g/100 mL (0 °C) 121 g/100 mL (25 °C) 138.3 g/100 mL (50 °C) 162.9 g/100 mL (100 °C) | |
| Solubility | soluble in alcohol, glycerol insoluble in ether, liquid ammonia |
| Solubility in methanol | 55 g/100 g (28 °C) |
| Solubility in isopropanol | ~14 g / 100 g (28 °C) |
| Acidity (pKa) | 14.7 |
| −22.0·10−6 cm3/mol | |
Refractive index (nD) |
1.409 (20 °C) |
| Thermochemistry | |
Heat capacity (C) |
65.87 J/mol·K |
Std molar entropy (S⦵298) |
79.32 J/mol·K |
Std enthalpy of formation (ΔfH⦵298) |
-425.8 kJ/mol |
Gibbs free energy (ΔfG⦵) |
-380.2 kJ/mol |
| Hazards | |
| GHS labelling: | |
| Danger | |
| H290, H302, H314 | |
| P280, P305+P351+P338, P310 | |
| NFPA 704 (fire diamond) | |
| Flash point | nonflammable |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) |
273 mg/kg (oral, rat) |
| NIOSH (US health exposure limits): | |
PEL (Permissible) |
none |
REL (Recommended) |
C 2 mg/m3 |
IDLH (Immediate danger) |
N.D. |
| Safety data sheet (SDS) | ICSC 0357 |
| Related compounds | |
Other anions |
Potassium hydrosulfide Potassium amide |
Other cations |
Lithium hydroxide Sodium hydroxide Rubidium hydroxide Caesium hydroxide |
Related compounds |
Potassium oxide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references | |
Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utilize its caustic nature and its reactivity toward acids. An estimated 700,000 to 800,000 tonnes were produced in 2005. KOH is noteworthy as the precursor to most soft and liquid soaps, as well as numerous potassium-containing chemicals. It is a white solid that is dangerously corrosive.
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