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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(NO3)3 + 3 NH4OH → La(OH)3 + 3 NH4NO3

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

La2O3 + 3 H2O → 2 La(OH)3

Characteristics

Lanthanum hydroxide does not react much with alkaline substances, however is slightly soluble in acidic solution.³ 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 → − H 2 O 330   o C   {\displaystyle \mathrm {{\xrightarrow[{-H_{2}O}]{330\ ^{o}C}}\ } } LaOOH 2 LaOOH → − H 2 O Δ   {\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

External links

• "Lanthanum - Element information, properties and uses - Periodic Table". rsc.org.
• External MSDS 1
• External MSDS 2
• Lanthanum Oxide MSDS

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. /wiki/Doi_(identifier) ↩

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. /wiki/Doi_(identifier) ↩

3. 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. /wiki/Doi_(identifier) ↩

4. Michael E. Brown, Patrick Kent Gallagher (2008). Handbook of Thermal Analysis and Calorimetry. Elsevier. p. 482. ISBN 978-0-44453123-0. 978-0-44453123-0 ↩

5. 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. /wiki/Doi_(identifier) ↩