Бериллия гидроксид

Химические свойства

White powder. Decomposes to the oxide at 138C. Soluble in acids and alkalies; insoluble in water.

Физические свойства

Beryllium Hydroxide can be prepared by reacting the oxide with water:
BeO＋H2O→Be(OH)2
If heated, it decomposes at 1273°C. Its solubility in water is slight and its solubility product Ksp(H2O) is 6.92×10^-22. It is soluble in acids and bases.
Beryllium hydroxide exists in three forms: as a metastable tetragonal crystalline solid (a-Be(OH)2; as a stable orthorhombic crystalline solid (b-Be(OH)2); and in a slightly basic pH, it appears as a slimy, gelatinous substance (Be(OH)4^2-).

Использование

Beryllium hydroxide is a strategic component concerning the usage of beryllium metal and its compounds in industry. Beryllium hydroxide is the key compound used to prepare a variety of beryllium products.Note that Be(OH)2 is the primary product used to prepare the metal and various beryllium salts.
The largest usage of beryllium hydroxide is to make the oxide or the metal that is used in many industries. The total tonnage is not large but substantial. Beryllium hydroxide is available commercially in large quantities.

Определение

beryllium hydroxide: A whitecrystalline compound, Be(OH)₂, precipitatedfrom solutions of berylliumsalts by adding alkali. Like the oxide,it is amphoteric and dissolves in excessalkali to give beryllates.

Подготовка

Beryllium hydroxide, Be(OH)2, is an amphoteric hydroxide, dissolving in both acids and alkalis. Industrially it is produced as a by-product in the extraction of beryllium metal from the ores, “beryl” and “bertrandite” When alkali is added to beryllium salt solutions, the a-form (a gel) is formed. If this left to stand or boiled the rhombic b-form precipitates. This has the Zn(OH)2 structure with tetrahedral beryllium centers. The alkali dissolution forms a “beryllate”:
2NaOH(aq)＋Be(OH)2(solid) → Na2Be(OH)4(aq)
With acids, beryllium salts are formed involving the Be(OH)＋ cation. With sulfuric acid, H2SO4:
2Be(OH)2＋H2SO4→[Be(OH)]2SO4＋ 2H2O
Thus, the probable formula for beryllium hydroxide is Be(OH)OH. However, this has never been reported. Beryllium hydroxide dehydrates completely at 400°C to form a white powder of acid soluble beryllium oxide:
Be(OH)2＋ heat → BeO＋H2O
Further heating at higher temperature produces acid insoluble BeO.

Опасность

Very toxic.

Профиль безопасности

Confirmed carcinogen withexperimental carcinogenic and tumorigenic data. Poisonby intravenous route. When heated to decomposition it emitsvery toxic fumes of BeO.