НИТРАТ БЕРИЛЛИЯ химические свойства, назначение, производство
Описание
Beryllium nitrate is said to have the molecular
formula of Be(NO3)2 and the molecular weight of grams
per mole. It is very soluble in water.
It could be prepared by the action of nitric acid on
beryllium carbonate, oxide or hydroxide:
BeCO3 + 2HNO3 ? Be(NO3)2 + CO2 +H2O
Be(OH)2 + 2HNO3 ? Be(NO3)2 + 2H2O
It is described as Be(NO3)2·4H2O, a compound that
forms colorless, deliquescent crystals that are soluble in
water, and used to introduce beryllium oxide into materials used in incandescent mantles. However, in
view of recent developments concerning the behavior
of the Be3+ cation in solution, the more likely reactions
are:
BeCO3 + 2HNO3 ? Be(OH)NO3 + CO2 + 1/2H2O
Be(OH)2 + 2HNO3 ? Be(OH)NO3 + 3/2H2O
Химические свойства
White to faintly yellowish, deliquescent
mass. Soluble in
water, alcohol.
Физические свойства
DTA analysis of the tetrahydrate showed that it
dissolves in its own waters of hydration at about
60.4°C. Heating above 101°C causes decomposition
with loss of water and oxides of nitrogen plus formation
of the oxide. The decomposition is complete at 250°C.
Thermal decomposition of these salt hydrates occurs
by release of nitric acid which then breaks down to
form the nitrogen oxides, rather than break down of
the nitrate anion itself. The anhydrate has been prepared
by the reaction of beryllium chloride with N2O4 dissolved
in ethylacetate. If heated in a vacuum above
50°C, the product, Be(NO3)2·2N2O4, evolves oxides of
nitrogen to produce the anhydrate.
The tetrahydrate has a CAS number of 13597-99-4 and
molecular weight is grams per mole. Anhydrous beryllium
nitrate is a white to pale yellow crystalline solid.
Beryllium nitrate trihydrate (CAS number = 7787-55-5)
forms slightly yellow crystals with a vapor pressure
49.8 mm Hg at 25°C. Its melting point is 60.5°C and it
decomposes completely at 102.3°C. Its Enthalpy of
vaporization = 37.72 kJ/mol and its boiling point is
83°C at 760 mm Hg where it becomes anhydrous. Beryllium
nitrate is a tumorigen, mutagen and reproductive
effector in rats and, presumably in humans.
Beryllium metal dissolves readily in nonoxidizing
acids such as HCl and H2SO4, but not in nitric acid as this forms the oxide (this behavior is similar to that of
aluminum metal). Beryllium, again similarly to
aluminum, dissolves in warm alkali to form the beryllate
anion, Be(OH)42-, and hydrogen gas.
Использование
Beryllium nitrate is used as a hardening agent for mantles on gas lanterns.
Подготовка
Anhydrous beryllium nitrate has been prepared by the reaction of anhydrous beryllium chloride with an ethylacetate-dinitrogen tetroxide mixture to give Be(NO3)2 · 2N2O4 [Addison and Walker 1963]. When heated above 50 °C (120 °F) in a vacuum, oxides of nitrogen are evolved, leaving anhydrous beryllium nitrate. The anhydrous salt is stable to approximately 125 °C (255 °F), when a sudden decomposition occurs to give nitrogen tetroxide and a volatile compound that separates from the gas phase as colorless Be4O(NO3)6 crystals. These crystals are slowly hydrolyzed when added to water.
Опасность
Beryllium nitrate is a toxic chemical,like all other beryllium compounds. It is also an irritant in small doses. When burned, it gives off irritating or toxic fumes. However, when massive short-term exposure occurs, acute pneumonitis can set in, but symptoms do not manifest themselves for 3 days.
Профиль безопасности
Confirmed carcinogen. Poison byintraperitoneal, intravenous, and subcutaneous routes.Experimental reproductive effects. When heated todecomposition it emits very toxic fumes of BeO and NOx.
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