Beryllium hydroxide, Be(OH)
2, is an
amphoteric
In chemistry, an amphoteric compound () is a molecule or ion that can react both as an acid and as a base. What exactly this can mean depends on which definitions of acids and bases are being used.
One type of amphoteric species are amphipro ...
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. ...
, dissolving in both
acid
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a se ...
s and
alkali
In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic 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 ...
s. Industrially, it is produced as a by-product in the extraction of beryllium metal from the ores
beryl
Beryl ( ) is a mineral composed of beryllium aluminium silicate with the chemical formula Be3Al2Si6O18. Well-known varieties of beryl include emerald and aquamarine. Naturally occurring, hexagonal crystals of beryl can be up to several ...
and
bertrandite
Bertrandite is a beryllium sorosilicate hydroxide mineral with composition: Be4Si2O7(OH)2. Bertrandite is a colorless to pale yellow orthorhombic mineral with a hardness of 6-7.
It is commonly found in beryllium rich pegmatites and is in part an ...
. The natural pure beryllium hydroxide is rare (in form of the mineral behoite, orthorhombic) or very rare (clinobehoite, monoclinic).
[Mindat, http://www.mindat.org/min-1066.html] 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.
[Mary Eagleson, 1994, Concise encyclopedia chemistry, Walter de Gruyter, ] This has the same structure as
zinc hydroxide, Zn(OH)
2, with tetrahedral beryllium centers.
Reactions
Beryllium hydroxide is difficult to dissolve in water. With alkalis it dissolves to form the tetrahydroxoberyllate/tetrahydroxidoberyllate anion,
4">e(OH)4sup>2−.
[Egon Wiberg, Arnold Frederick Holleman (2001) ''Inorganic Chemistry'', Elsevier ] With
sodium hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions .
Sodium hydroxide is a highly caustic base and al ...
solution:
:2 NaOH(aq) + Be(OH)
2(s) → Na
2 4">e(OH)4aq)
With acids, beryllium salts are formed.
For example, with
sulfuric acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular fo ...
, H
2SO
4,
beryllium sulfate
Beryllium sulfate normally encountered as the tetrahydrate, e(H2O)4O4 is a white crystalline solid. It was first isolated in 1815 by Jons Jakob Berzelius. Beryllium sulfate may be prepared by treating an aqueous solution of many beryllium salts ...
is formed:
:Be(OH)
2 + H
2SO
4 → BeSO
4 + 2 H
2O
Beryllium hydroxide dehydrates at 400 °C to form the soluble white powder,
beryllium oxide
Beryllium oxide (BeO), also known as beryllia, is an inorganic compound with the formula BeO. This colourless solid is a notable electrical insulator with a higher thermal conductivity than any other non-metal except diamond, and exceeds that of ...
:
:Be(OH)
2 → BeO + H
2O
Further heating at higher temperature produces acid insoluble BeO.
References
{{Hydroxides
Amphoteric compounds
Beryllium compounds
Hydroxides