Lanthanum hydroxide

Lanthanum hydroxide is La(OH)
₃, a hydroxide of the rare-earth element lanthanum.

Lanthanum(III) hydroxide

__ La3+     __ OH−
Names
IUPAC name Lanthanum(III) hydroxide
Identifiers
CAS Number	14507-19-8 Y
3D model (JSmol)	Interactive image
ChemSpider	119053
ECHA InfoCard	100.034.994
EC Number	238-510-2
PubChem CID	135111
UNII	7PTY21U5YN Y
CompTox Dashboard (EPA)	DTXSID5065778
InChI InChI=1S/La.3H2O/h;3*1H2 Key: YXEUGTSPQFTXTR-UHFFFAOYSA-K
SMILES [OH-].[OH-].[OH-].[La+3]
Properties
Chemical formula	La(OH)3
Molar mass	189.93 g/mol
Solubility in water	Ksp= 2.00·10−21
Structure
Crystal structure	hexagonal
Space group	P63/m, No. 176
Lattice constant	a = 6.547 Å, c = 3.854 Å
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Irritant
GHS labelling:[1]
Pictograms
Signal word	Danger
Hazard statements	H314
Precautionary statements	P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501
NFPA 704 (fire diamond)	1 W
Flash point	Non-flammable
Related compounds
Other anions	Lanthanum(III) chloride
Other cations	Cerium(III) hydroxide Actinium(III) hydroxide
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

Synthesis

Lanthanum hydroxide can be obtained by adding an alkali such as ammonia to aqueous solutions of lanthanum salts such as lanthanum nitrate. This produces a gel-like precipitate that can then be dried in air.^[2]

La(NO₃)₃ + 3 NH₄OH → La(OH)₃ + 3 NH₄NO₃

Alternatively, it can be produced by hydration reaction (addition of water) to lanthanum oxide.^[3]

La₂O₃ + 3 H₂O → 2 La(OH)₃

Characteristics

Lanthanum hydroxide does not react much with alkaline substances, however is slightly soluble in acidic solution.^[2] In temperatures above 330 °C it decomposes into lanthanum oxide hydroxide (LaOOH), which upon further heating decomposes into lanthanum oxide (La₂O₃):^[4]

La(OH)₃ ${\displaystyle \mathrm {{\xrightarrow[{-H_{2}O}]{330\ ^{o}C}}\ } }$ LaOOH

2 LaOOH ${\displaystyle \mathrm {{\xrightarrow[{-H_{2}O}]{\Delta }}\ } }$ La₂O₃

Lanthanum hydroxide crystallizes in the hexagonal crystal system. Each lanthanum ion in the crystal structure is surrounded by nine hydroxide ions in a tricapped trigonal prism.^[5]