Lanthanum hydroxide is , a
hydroxide
Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It ...
of the
rare-earth element
The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set o ...
lanthanum
Lanthanum is a chemical element; it has symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements bet ...
.
Synthesis
Lanthanum hydroxide can be obtained by adding an
alkali
In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The a ...
such as
ammonia
Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...
to aqueous solutions of
lanthanum salt
Lanthanum is a chemical element; it has symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements betw ...
s such as
lanthanum nitrate
Lanthanum(III) nitrate is any inorganic compound with the chemical formula . It is used in the extraction and purification of lanthanum from its ores.
The compound decomposes at 499°C to lanthanum oxide, nitric oxide and oxygen.
Preparation
La ...
. This produces a gel-like
precipitate
In an aqueous solution, precipitation is the "sedimentation of a solid material (a precipitate) from a liquid solution". The solid formed is called the precipitate. In case of an inorganic chemical reaction leading to precipitation, the chemic ...
that can then be dried in air.
:
Alternatively, it can be produced by
hydration reaction
In chemistry, a hydration reaction is a chemical reaction in which a substance combines with water. In organic chemistry, water is added to an unsaturated substrate, which is usually an alkene or an alkyne. This type of reaction is employed indust ...
(addition of water) to
lanthanum oxide
Lanthanum(III) oxide, also known as lanthana, chemical formula , is an inorganic compound containing the rare earth element lanthanum and oxygen. It is used in some ferroelectric materials, as a component of optical materials, and is a feedstock ...
.
:
Characteristics
Lanthanum hydroxide does not react much with alkaline substances, however is slightly soluble in acidic solution.
In temperatures above 330 °C it decomposes into lanthanum oxide hydroxide (LaOOH), which upon further heating decomposes into lanthanum oxide ():
:
LaOOH
:2 LaOOH
Lanthanum hydroxide crystallizes in the
hexagonal crystal system
In crystallography, the hexagonal crystal family is one of the six crystal family, crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the tr ...
. Each lanthanum ion in the crystal structure is surrounded by nine hydroxide ions in a
tricapped trigonal prism
The triaugmented triangular prism, in geometry, is a convex polyhedron with 14 equilateral triangles as its faces. It can be constructed from a triangular prism by attaching equilateral square pyramids to each of its three square faces. The same ...
.
References
External links
*
External MSDS 1 Lanthanum Oxide MSDS
Lanthanum compounds
Inorganic compounds
Hydroxides
{{inorganic-compound-stub