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Физические свойства
Barium Oxide is
a white, hygroscopic formed by the burning of Ba metal
in oxygen or the decomposition of the carbonate salt:
2Ba＋ O2→2BaO
BaCO3→BaO＋ CO2
It transforms into the hydroxide on contact with
water.
BaO＋H2O→Ba(OH)2
It is soluble in
ethanol, dilute acids and alkalis but insoluble in acetone
and liquid ammonia.
The monoxide is formed when the metal burns
in air, but is usually prepared by the ignition of the
nitrate, oxygen and oxides of nitrogen being liberated.
It can also be obtained by the ignition of an intimate
mixture of the carbonate and carbon, and in small quantities
by the ignition of the iodate.
Использование
Barium oxide is used as a coating for “hot cathodes”
in a variety of electronic devices such as TV’s and lamps.
It replaced lead oxide in the production of certain kinds
of glass. While lead oxide raised the refractive index of
the glass, it also raised the dispersion, i.e refraction of
various colors of light resulting in distortion of images
which barium oxide does not alter. Barium oxide also
has use as an ethoxylation catalyst in the reaction of ethylene oxide and alcohols which takes place between
150 and 200°C.
The thermionic emission from thin evaporated films
of barium oxide has been studied extensively. Thin
barium oxide films have a good emission following
evaporation. The emission improves a little during
heat treatment, and is then similar to that from a sprayed
cathode coating of barium oxide.
Определение
barium oxide: A white or yellowishsolid, BaO, obtained by heating bariumin oxygen or by the thermal decompositionof barium carbonate ornitrate; cubic; r.d. 5.72; m.p. 1923°C;b.p. 2000°C. When barium oxide isheated in oxygen the peroxide, BaO2,is formed in a reversible reactionthat was once used as a method forobtaining oxygen (the Brin process).Barium oxide is now used in themanufacture of lubricating-oil additives.
Подготовка
Barium oxide is made by heating barium carbonate with coke, carbon black or tar:
BaCO3 + C→ BaO + 2CO
It may be also prepared by thermal decomposition of barium nitrate.
Общее описание
A white to yellow powder. May be toxic by ingestion. Irritates skin, eyes and mucous membranes. Used as a drying agent for gasoline and solvents.
Реакции воздуха и воды
Hygroscopic. Reacts readily and exothermically with water to form a solution of corrosive barium hydroxide [Merck 11th ed. 1989].
Профиль реактивности
BARIUM OXIDE reacts as a strong base. Combines exothermically with all categories of acids. Reacts with carbon dioxide to form barium carbonate [Merck 11th ed. 1989]. Ignites hydroxylamine on contact [Mellor 8:291 1946-47]. Mixtures with mercurous or nickel oxide react vigorously with hydrogen sulfide in air. Explosions may result [Mellor 10:140 1946-47]. Can react, particularly in the presence of moisture, with aluminum and zinc)to form oxides or hydroxides of the metal and generate gaseous hydrogen. May initiate polymerization reactions in polymerizable organic compounds, especially epoxides. May generate flammable and/or toxic gases with ammonium salts, nitrides, halogenated organics, peroxides, and hydroperoxides.
Опасность
Toxic by ingestion. See barium.
Угроза здоровью
TOXIC; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance may cause severe injury, burns or death. Reaction with water or moist air will release toxic, corrosive or flammable gases. Reaction with water may generate much heat that will increase the concentration of fumes in the air. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.
Пожароопасность
Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Vapors may accumulate in confined areas (basement, tanks, hopper/tank cars etc.). Substance will react with water (some violently), releasing corrosive and/or toxic gases and runoff. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated or if contaminated with water.
Профиль безопасности
A poison via
subcutaneous route. See also BARIUM
COMPOUNDS (soluble). Combustible by
spontaneous chemical reaction; produces
heat on contact with water or steam. Reacts
with H2O, Ba(OH)2. Incompatible with H2S,
hydroxylamine, N2O4, triuranium octaoxide,
so3.
Возможный контакт
It is used to dry gases and solvents
and in producing detergents for lubricating oils.
Перевозки
UN1884 Barium oxide, Hazard Class: 6.1;
Labels: 6.1—Poisonous materials.
Несовместимости
Reacts with water, forming the strong
base, barium hydroxide. Keep away from acids, hydrogen
sulfide, carbon dioxide; hydroxylamine, nitrogen tetroxide;
sulfur trioxide; since violent reactions occur. Reacts with
triuranium. Never pour water into this chemical.
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