Copper hydroxide

Copper(II) hydroxide

Names
IUPAC name Copper(II) hydroxide
Other names Cupric hydroxide
Identifiers
CAS Number	20427-59-2 Y
3D model (JSmol)	Interactive image
ChemSpider	144498 Y
ECHA InfoCard	100.039.817
KEGG	C18712 Y
PubChem CID	164826
UNII	3314XO9W9A N
InChI InChI=1S/Cu.2H2O/h;2*1H2/q+2;;/p-2 Y Key: JJLJMEJHUUYSSY-UHFFFAOYSA-L Y InChI=1/Cu.2H2O/h;2*1H2/q+2;;/p-2 Key: JJLJMEJHUUYSSY-NUQVWONBAH
SMILES [Cu+2].[OH-].[OH-]
Properties
Chemical formula	Cu(OH)2
Molar mass	97.561 g/mol
Appearance	Blue or blue-green solid
Density	3.368 g/cm3, solid
Melting point	80 °C (176 °F; 353 K) (decomposes into CuO)
Solubility in water	negligible
Solubility product (Ksp)	2.20 x 10−20
Solubility	insoluble in ethanol; soluble in NH4OH, KCN
Magnetic susceptibility (χ)	+1170.0·10−6 cm3/mol
Thermochemistry
Std molar entropy (So298)	108 J·mol−1·K−1
Std enthalpy of formation (ΔfHo298)	−450 kJ·mol−1
Hazards
Main hazards	Skin, Eye, & Respiratory Irritant
Safety data sheet	http://www.sciencelab.com/xMSDS-Cupric_Hydroxide-9923594
NFPA 704	0 2 0
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD50 (median dose)	1000 mg/kg (oral, rat)
US health exposure limits (NIOSH):
PEL (Permissible)	TWA 1 mg/m3 (as Cu)
REL (Recommended)	TWA 1 mg/m3 (as Cu)
IDLH (Immediate danger)	TWA 100 mg/m3 (as Cu)
Related compounds
Other anions	Copper(II) oxide Copper(II) carbonate Copper(II) sulfate Copper(II) chloride
Other cations	Nickel(II) hydroxide Zinc hydroxide Iron(II) hydroxide Cobalt hydroxide
Related compounds	Copper(I) oxide Copper(I) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Copper(II) hydroxide is the hydroxide of copper with the chemical formula of Cu(OH)₂. It is a pale blue solid. Some forms of copper(II) hydroxide are sold as "stabilized" copper hydroxide, although they likely consist of a mixture of copper(II) carbonate and hydroxide. Copper hydroxide is a weak base.

Copper(II) hydroxide has been known since copper smelting began around 5000 BC although the alchemists were probably the first to manufacture it by mixing solutions of lye (sodium or potassium hydroxide) and blue vitriol (copper(II) sulfate). Sources of both compounds were available in antiquity.

It was produced on an industrial scale during the 17th and 18th centuries for use in pigments such as blue verditer and Bremen green. These pigments were used in ceramics and painting.

Copper(II) hydroxide can be produced by adding a sodium hydroxide to a dilute solution of copper(II) sulfate (CuSO₄·5H₂O). The precipitate produced in this manner, however, often contains water and an appreciable amount of sodium hydroxide impurity. A purer product can be attained if ammonium chloride is added to the solution beforehand. Alternatively, copper hydroxide is readily made by electrolysis of water (containing a little electrolyte such as sodium sulfate, or magnesium sulfate). A copper anode is used, often made from scrap copper.

The mineral of the formula Cu(OH)₂ is called spertiniite. Copper(II) hydroxide is rarely found as an uncombined mineral because it slowly reacts with carbon dioxide from the atmosphere to form a basic copper(II) carbonate. Thus copper slowly acquires a dull green coating in moist air by the reaction: