Beryllium hydroxide

Crystal structure
__ Be 2+      __ O 2−      __ H +
General
Surname	Beryllium hydroxide
other names	Beryllium dihydroxide
Ratio formula	Be (OH) 2
Brief description	colorless gel
External identifiers / databases
CAS number 13327-32-7 EC number 236-368-6 ECHA InfoCard 100,033,048 PubChem 25879 Wikidata Q419729
properties
Molar mass	43.03 g mol −1
Physical state	firmly
density	1.924 g cm −3
solubility	hardly soluble in water
safety instructions
GHS labeling of hazardous substances Beryllium compounds danger H and P phrases H: 350i-330-301-372-319-335-315-317-411 P: ?
Thermodynamic properties
ΔH f 0	−902.5 kJ / mol
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Beryllium hydroxide is a chemical compound from the group of hydroxides .

Occurrence

Beryllium hydroxide occurs naturally in the form of the rare to very rare minerals behoite and clinobehoite .

Extraction and presentation

Beryllium hydroxide can be obtained by precipitation from a beryllium salt solution by adding ammonia solution or a solution of a metal hydroxide.

${\displaystyle \mathrm {Be^{2+}\ +\ 2\ OH^{-}\longrightarrow Be(OH)_{2}} }$

However, better manage the presentation of crystalline beryllium hydroxide from a hot saturated solution of amorphous Be (OH) ₂ in a 10 n NaOH solution, via the intermediate step of the formation of Natriumtetrahydroxoberyllat and subsequent slow cooling.

properties

Beryllium hydroxide is a colorless gel that is practically insoluble in water. When heated above 400 ° C it decomposes to beryllium oxide :

${\displaystyle \mathrm {Be(OH)_{2}\longrightarrow BeO+H_{2}O} }$

It occurs in two modifications, α- and β-beryllium hydroxide. The compound is amphoteric in the freshly precipitated state , so it dissolves both in acids with the formation of [Be (H ₂ O) ₄ ] ²⁺ , and in alkaline solutions with the formation of [Be (OH) ₄ ] ²⁻ . When boiling with water, when drying or when left to stand for a long time, the compound "ages" and becomes sparingly soluble. It is the only amphoteric hydroxide of the alkaline earth metals.

In the orthorhombic crystal structure of beryllium hydroxide, each beryllium ion is coordinated by four hydroxide ions, which form an only slightly distorted tetrahedron . Since each hydroxide ion is bound to two Be ²⁺ ions, a three-dimensional network of corner-linked tetrahedra is created. Numerous hydrogen bonds exist between the hydroxide ions .

Individual evidence

1. ↑ Entry on beryllium compounds. In: Römpp Online . Georg Thieme Verlag, accessed on March 3, 2012.
2. ↑ Roger Blachnik (Ed.): Paperback for chemists and physicists . Volume III: Elements, Inorganic Compounds and Materials, Minerals . founded by Jean d'Ans, Ellen Lax. 4th, revised and revised edition. Springer, Berlin 1998, ISBN 3-540-60035-3 , pp. 334 ( limited preview in Google Book search).
3. ↑ ^{a b c d e} Egon Wiberg, Arnold Frederick Holleman: Inorganic Chemistry , Elsevier, 2001, ISBN 0-12352651-5 .
4. ^ Entry on beryllium compounds in the GESTIS substance database of the IFA , accessed on August 24, 2016(JavaScript required) .
5. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-6.
6. ↑ Mineral Atlas: Behoit
7. ↑ Behoite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 69 kB ; accessed on November 22, 2017]).
8. ↑ Mineralienatlas: Klinobehoit
9. ↑ Clinobehoite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 69 kB ; accessed on November 22, 2017]).
10. ↑ Georg Brauer (Ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume II, Ferdinand Enke, Stuttgart 1978, ISBN 3-432-87813-3 , p. 893.
11. ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 , p. 1106.
12. ^ Charles E. Mortimer, Ulrich Müller, Johannes Beck: Chemistry: The basic knowledge of chemistry . Georg Thieme Verlag, 2014, ISBN 3-13-171331-3 , p. 473 ( limited preview in Google Book search).
13. ↑ R. Stahl, C. Jung, HD Lutz, W. Kockelmann H. Jacobs: Crystal structures and hydrogen bonds in β-Be (OH) ₂ and ε-Zn (OH) ₂ . In: Journal of Inorganic and General Chemistry . 624, 1998, p. 1130.