Potassium hydroxide pure (KOH)

Potassium hydroxide

IUPAC name

Potassium hydroxide

Other names

Caustic potash, Potash lye, Potassia, Potassium hydrate

Identifiers

CAS number

1310-58-3 

PubChem

14797

ChemSpider

14113 

UNII

WZH3C48M4T 

EC number

215-181-3

UN number

1813

ChEBI

CHEBI:32035 

RTECS number

TT2100000

Properties

Molecular formula

HKO

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

406 °C (763 °F; 679 K)

Boiling point

1,327 °C (2,421 °F; 1,600 K)

Solubility in water

85 g/100 g (-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)

Acidity (pK_a)

13.5 (0.1 M)

Refractive index (n_D)

1.409 (20 °C)

Structure

Crystal structure

rhombohedral

Thermochemistry

Specific
heat capacity C

65.87 J/mol·K

Std molar
entropy S^o₂₉₈

79.32 J/mol·K

Std enthalpy of
formation Δ_fH^o₂₉₈

-425.8 kJ/mol

Gibbs free energy ΔG

-380.2 kJ/mol

Hazards

GHS pictograms

GHS signal word

Danger

GHS hazard statements

H302, H314

GHS precautionary statements

P280, P305+351+338, P310

EU Index

019-002-00-8

EU classification

C Xn

R-phrases

R22, R35

S-phrases

(S1/2), S26, S36/37/39, S45

Flash point

Non-flammable

LD₅₀

273 mg/kg (rat, oral)

Related compounds

Other anions

Potassium hydrosulfide
Potassium amide

Other cations

Lithium hydroxide
Sodium hydroxide
Rubidium hydroxide
Caesium hydroxide

Related compounds

Potassium oxide

Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)