Potassium hydroxide

Potassium hydroxide
Names
	IUPAC name Potassium hydroxide
	Other names Caustic potash; Lye; Potash lye; Potassia; Potassium hydrate; KOH;
Identifiers
CAS Number	1310-58-3 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:32035 ;
ChemSpider	14113 ;
ECHA InfoCard	100.013.802
EC Number	215-181-3;
E number	E525 (acidity regulators, ...)
PubChem CID	14797;
RTECS number	TT2100000;
UNII	WZH3C48M4T ;
UN number	1813
CompTox Dashboard (EPA)	DTXSID5029633 ;
	InChI InChI=1S/K.H2O/h;1H2/q+1;/p-1 Key: KWYUFKZDYYNOTN-UHFFFAOYSA-M ; InChI=1/K.H2O/h;1H2/q+1;/p-1 Key: KWYUFKZDYYNOTN-REWHXWOFAT;
	SMILES [K+].[OH-];
Properties
Chemical formula	KOH
Molar mass	56.105 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)
Solubility in water	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
Magnetic susceptibility (χ)	−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:
Pictograms
Signal word	Danger
Hazard statements	H290, H302, H314
Precautionary statements	P280, P305+P351+P338, P310
NFPA 704 (fire diamond)	3 0 1 ALK
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). verify (what is ?) Infobox references

Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash.

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. About 2.5 million tonnes were produced in 2023.^[11] 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.^[12]

^ ^a ^b Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton, Florida: CRC Press. p. 4-80. ISBN 0-8493-0486-5.
^ ^a ^b ^c ^d ^e ^f "potassium hydroxide". chemister.ru. Archived from the original on 18 May 2014. Retrieved 8 May 2018.
^ Otto, H.W; Seward, R.P. (1964). "Phase equilibria in the potassium hydroxide-sodium hydroxide system". J. Chem. Eng. Data. 9 (4): 507–508. doi:10.1021/je60023a009.
^ Seward, R.P; Martin, K.E. (1949). "The melting point of potassium hydroxide". J. Am. Chem. Soc. 71 (10): 3564–3565. Bibcode:1949JAChS..71R3564S. doi:10.1021/ja01178a530.
^ Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds. Van Nostrand. Retrieved 2014-05-29.
^ Popov, K.; et al. (2002). "⁷Li, ²³Na, ³⁹K and ¹³³Cs NMR comparative equilibrium study of alkali metal cation hydroxide complexes in aqueous solutions. First numerical value for CsOH formation". Inorganic Chemistry Communications. 3 (5): 223–225. doi:10.1016/S1387-7003(02)00335-0. ISSN 1387-7003. Retrieved October 20, 2018.
^ ^a ^b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A22. ISBN 978-0-618-94690-7.
^ ^a ^b ^c Sigma-Aldrich Co., Potassium hydroxide. Retrieved on 2014-05-18.
^ ^a ^b ^c NIOSH Pocket Guide to Chemical Hazards. "#0523". National Institute for Occupational Safety and Health (NIOSH).
^ Chambers, Michael. "ChemIDplus - 1310-58-3 - KWYUFKZDYYNOTN-UHFFFAOYSA-M - Potassium hydroxide [JAN:NF] - Similar structures search, synonyms, formulas, resource links, and other chemical information". chem.sis.nlm.nih.gov. Archived from the original on 12 August 2014. Retrieved 8 May 2018.
^ Chen, Fernando (2025-03-21). "Potassium Hydroxide (KOH): The "Alkaline Engine" Driving Modern Industry". Kelewell Trading. Retrieved 2025-08-11.
^ Schultz, Heinz; Bauer, Günter; Schachl, Erich; Hagedorn, Fritz; Schmittinger, Peter (2005). "Potassium Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim, Germany: Wiley-VCH. doi:10.1002/14356007.a22_039. ISBN 978-3-527-30673-2.

[crc-1] Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton, Florida: CRC Press. p. 4-80. ISBN 0-8493-0486-5.

[chemister-2] ^ ^a ^b ^c ^d ^e ^f "potassium hydroxide". chemister.ru. Archived from the original on 18 May 2014. Retrieved 8 May 2018.

[3] Otto, H.W; Seward, R.P. (1964). "Phase equilibria in the potassium hydroxide-sodium hydroxide system". J. Chem. Eng. Data. 9 (4): 507–508. doi:10.1021/je60023a009.

[4] Seward, R.P; Martin, K.E. (1949). "The melting point of potassium hydroxide". J. Am. Chem. Soc. 71 (10): 3564–3565. Bibcode:1949JAChS..71R3564S. doi:10.1021/ja01178a530.

[sioc-5] Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds. Van Nostrand. Retrieved 2014-05-29.

[6] Popov, K.; et al. (2002). "⁷Li, ²³Na, ³⁹K and ¹³³Cs NMR comparative equilibrium study of alkali metal cation hydroxide complexes in aqueous solutions. First numerical value for CsOH formation". Inorganic Chemistry Communications. 3 (5): 223–225. doi:10.1016/S1387-7003(02)00335-0. ISSN 1387-7003. Retrieved October 20, 2018.

[b1-7] Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A22. ISBN 978-0-618-94690-7.

[sigma-8] Sigma-Aldrich Co., Potassium hydroxide. Retrieved on 2014-05-18.

[PGCH-9] NIOSH Pocket Guide to Chemical Hazards. "#0523". National Institute for Occupational Safety and Health (NIOSH).

[10] Chambers, Michael. "ChemIDplus - 1310-58-3 - KWYUFKZDYYNOTN-UHFFFAOYSA-M - Potassium hydroxide [JAN:NF] - Similar structures search, synonyms, formulas, resource links, and other chemical information". chem.sis.nlm.nih.gov. Archived from the original on 12 August 2014. Retrieved 8 May 2018.

[:0-11] Chen, Fernando (2025-03-21). "Potassium Hydroxide (KOH): The "Alkaline Engine" Driving Modern Industry". Kelewell Trading. Retrieved 2025-08-11.

[Ullmann-12] Schultz, Heinz; Bauer, Günter; Schachl, Erich; Hagedorn, Fritz; Schmittinger, Peter (2005). "Potassium Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim, Germany: Wiley-VCH. doi:10.1002/14356007.a22_039. ISBN 978-3-527-30673-2.

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