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. I ...
, 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 sequ ...
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 mete ...
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
Zinc hydroxide Zn( OH)2 is an inorganic chemical compound. It also occurs naturally as 3 rare minerals: wülfingite (orthorhombic), ashoverite and sweetite (both tetragonal).
Like the hydroxides of other metals, such as lead, aluminium, beryll ...
, 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 alkali ...
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 formu ...
, 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