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
ChemSpider
ECHA InfoCard 100.034.994
EC Number
  • 238-510-2
UNII
Properties
La(OH)3
Molar mass 189.93 g/mol
Ksp= 2.00·10−21
Structure
hexagonal
P63/m, No. 176
a = 6.547 Å, c = 3.854 Å
Hazards
Main hazards Irritant
R-phrases (outdated) R36/37
S-phrases (outdated) S26, S22, S37/39
NFPA 704 (fire diamond)
Flammability (red): no hazard codeHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity (yellow): no hazard codeSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
1
Flash point Non-flammable
Related compounds
Other anions
 Lanthanum(III) chloride
Other cations
 Cerium(III) hydroxide
Scandium(III) hydroxide
Yttrium(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.[1]

La(NO
3)
3 + 3 NH
4OH → La(OH)
3 + 3 NH
4NO
3

Alternatively, it can be produced by hydration reaction (addition of water) to lanthanum oxide.[2]

La
2O
3 + 3 H
2O → 2 La(OH)
3

Characteristics

Lanthanum hydroxide does not react much with alkaline substances, however is slightly soluble in acidic solution.[1] In temperatures above 330 °C it decomposes into lanthanum oxide hydroxide (LaOOH), which upon further heating decomposes into lanthanum oxide (La
2O
3):[3]

La(OH)
3 LaOOH
2 LaOOH La
2O
3

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.[4]

References
  1. E.V. Shkolnikov (2009). "Thermodynamic Characterization of the Amphoterism of Hydroxides and Oxides of Scandium Subgroup Elements in Aqueous Media". Russian Journal of Applied Chemistry. 82 (2): 2098–2104. doi:10.1134/S1070427209120040. S2CID 93220420.
  2. Ding, Jiawen; Wu, Yanli; Sun, Weili; Li, Yongxiu (2006). "Preparation of La(OH)3 and La2O3 with Rod Morphology by Simple Hydration of La2O3". Journal of Rare Earths. 24 (4): 440–442. doi:10.1016/S1002-0721(06)60139-7.
  3. Michael E. Brown, Patrick Kent Gallagher. Handbook of Thermal Analysis and Calorimetry. p. 482. ISBN 978-0-44453123-0.
  4. Beall, G.W.; Milligan, W.O.; Wolcott, Herbert A. (1977). "Structural trends in the lanthanide trihydroxides". Journal of Inorganic and Nuclear Chemistry. 39 (1): 65–70. doi:10.1016/0022-1902(77)80434-X.


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