Barium oxide

Description

Barium oxide is a white to yellowish-white,odorless powder. Molecular weight=153.34; Freezing/Melting point=1923℃. Hazard Identification (based onNFPA-704 M Rating System): Health 3, Flammability 0,Reactivity 2 . Reacts violently with water.

Chemical Properties

Barium oxide is a white to yellowish-white, odorless powder.

Barium oxide is an alkaline earth flux that melts at 3493°F (1923C).It's an active flux at high temperatures and forms a strong eutectic with boron that can cause even matte glazes to run. Barium oxide gives strong, vivid colors, especially with copper and cobalt. It produces excellent satin and matte surfaces from crystallization. This is worth noting because alumina(in the form of clay) is also used to create matte surfaces, but only produces dull colors. With barium oxide you get both matte surfaces and vivid colors. It's sometimes used in small amounts to produce iron blue celadons. Barium oxide has a high viscosity and medium surface tension so it produces stiff glazes,but it will cause running in glazes that are fired too hot as its fluxing power increases with temperature. It has a medium expansion and contrac- tion rate.
Although barium oxide isn't volatile at ceramic temperatures keep in mind that it's extremely toxic, especially as a carbonate powder, when it becomes an airborne health hazard during mixing,and certainly if it leaches from a fired glaze. It was once used as a rat poison, so handle barium compounds with caution.Barium glazes aren't suitable for functional ware. Under laboratory conditions (i.e.. in pure water) barium carbonate is almost insoluble in water, but in acidic solutions it can become soluble, making it easier to absorb into the skin.
Barium sulfate is insoluble and even has medical uses. It's sometimes used to provide a less toxic form of barium oxide in glazes and clay bodies(as in Wedgwood's Jasperware), but it does release sulfur fumes when fired.
Soluble sources of barium oxide are barium carbonate (almost insoluble), and some frits (slightly soluble); an insoluble source of barium oxide is barium sulfate.

Physical properties

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.

Uses

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.

Uses

Barium oxide is used in cathode ray tubes, crown glass, and catalysts. It is used for the adsorption NO and NO2. It also plays an important role for NO2 storage and reduction. It acts as an efficient ethoxylation catalyst.

Uses

Porous grades are marketed especially for drying gases and solvents (particularly alcohols, aldehydes and petroleum solvents). Swells, but does not become sticky upon absorption of moisture. Used in manufacture of lubricating oil detergents. Also used for making barium methoxide.

Preparation

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.

Definition

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.

Definition

A barium-containing ore.

General Description

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.

Air & Water Reactions

Hygroscopic. Reacts readily and exothermically with water to form a solution of corrosive barium hydroxide [Merck 11th ed. 1989].

Reactivity Profile

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.

Hazard

Toxic by ingestion. See barium.

Health Hazard

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.

Fire Hazard

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.

Flammability and Explosibility

Non flammable

Safety Profile

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.

Potential Exposure

It is used to dry gases and solvents and in producing detergents for lubricating oils.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seekmedical attention immediately. If this chemical contactsthe skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove fromexposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing hasstopped and CPR if heart action has stopped. Transferpromptly to a medical facility. When this chemical hasbeen swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit. Medical observation is recommendedfor 24
48 h after breathing overexposure, as pulmonaryedema may be delayed. As first aid for pulmonary edema,a doctor or authorized paramedic may consider administering a corticosteroid spray. See also First Aid section in“Barium” entry.

storage

Color Code—Blue: Health Hazard/Poison: Storein a secure poison location. Store in tightly closed containers in a dry, cool, well-ventilated area away from water andthe incompatible substances cited above

Shipping

UN1884 Barium oxide, Hazard Class: 6.1; Labels: 6.1—Poisonous materials.

Incompatibilities

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.