Beryllium hydroxide

Beryllium hydroxide, Be(OH)₂, is an amphoteric hydroxide, dissolving in both acids and alkalis. Industrially, it is produced as a by-product in the extraction of beryllium metal from the ores beryl and bertrandite.^[7] The natural pure beryllium hydroxide is rare (in form of the mineral behoite, orthorhombic) or very rare (clinobehoite, monoclinic).^[8][9] When alkali is added to beryllium salt solutions the α-form (a gel) is formed. If this left to stand or boiled, the rhombic β-form precipitates.^[10] This has the same structure as zinc hydroxide, Zn(OH)₂, with tetrahedral beryllium centers.^[11]

Beryllium hydroxide

Names
IUPAC name Beryllium hydroxide
Other names Beryllic acid Hydrated beryllia
Identifiers
CAS Number	13327-32-7 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:35102 Y
ChemSpider	24110 N
ECHA InfoCard	100.033.048
EC Number	236-368-6
Gmelin Reference	1024
MeSH	Beryllium+hydroxide
PubChem CID	25879
RTECS number	DS3150000
UNII	2X0LRF1T6Q Y
CompTox Dashboard (EPA)	DTXSID80893932
InChI InChI=1S/Be.2H2O/h;2*1H2/q+2;;/p-2 Y Key: WPJWIROQQFWMMK-UHFFFAOYSA-L Y InChI=1/Be.2H2O/h;2*1H2/q+2;;/p-2 Key: WPJWIROQQFWMMK-NUQVWONBAB
SMILES O[Be]O
Properties
Chemical formula	BeH2O2
Molar mass	43.026 g·mol−1
Appearance	Vivid white, opaque crystals
Density	1.92 g cm−3[1]
Melting point	(decomposes)
Solubility in water	0.0000023965 g/L
Solubility product (Ksp)	6.92×10−22[2]
Acidity (pKa)	3.7[3]
Structure
Molecular shape	Linear
Thermochemistry
Heat capacity (C)	1.443 J K−1
Std molar entropy (S⦵298)	47 J·mol−1·K−1[4]
Std enthalpy of formation (ΔfH⦵298)	−904 kJ mol−1[4]
Gibbs free energy (ΔfG⦵)	−818 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Carcinogenic
GHS labelling:
Pictograms	[5]
Signal word	Danger
NFPA 704 (fire diamond)	4 0 0
Lethal dose or concentration (LD, LC):
LD50 (median dose)	4 mg kg−1 (intravenous, rat)
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 0.002 mg/m3 C 0.005 mg/m3 (30 minutes), with a maximum peak of 0.025 mg/m3 (as Be)[6]
REL (Recommended)	Ca C 0.0005 mg/m3 (as Be)[6]
IDLH (Immediate danger)	Ca [4 mg/m3 (as Be)][6]
Related compounds
Related compounds	Aluminium oxide Magnesium hydroxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Reactions

Beryllium hydroxide is difficult to dissolve in water. With alkalis it dissolves to form the tetrahydroxoberyllate (also known as tetrahydroxidoberyllate) anion, [Be(OH)₄]²⁻.^[12] With sodium hydroxide solution:

2 NaOH(aq) + Be(OH)₂(s) → Na₂[Be(OH)₄](aq)

With acids, beryllium salts are formed.^[12] For example, with sulfuric acid, H₂SO₄, beryllium sulfate is formed:

Be(OH)₂ + H₂SO₄ → BeSO₄ + 2 H₂O

Beryllium hydroxide dehydrates at 400 °C to form the soluble white powder, beryllium oxide:^[12]

Be(OH)₂ → BeO + H₂O

Further heating at higher temperature produces acid insoluble BeO.^[12]