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Barium oxide, also known as baria, is a white hygroscopic non-flammable compound with the formula BaO. It has a cubic structure and is used in cathode-ray tubes , crown glass, and catalysts. It is harmful to human skin and if swallowed in large quantity causes irritation.
Barium was identified as a new element in 1772, but not reduced to a metal until 1808 with the advent of electrolysis. Barium has few industrial applications. Historically, it was used as a getter for vacuum tubes and in oxide form as the emissive coating on indirectly heated cathodes.
The most common type of indirectly heated cathode is the oxide-coated cathode, in which the nickel cathode surface has a coating of alkaline earth metal oxide to increase emission. One of the earliest materials used for this was barium oxide; it forms a monatomic layer of barium with an extremely low work function.
Barium peroxide arises by the reversible reaction of O 2 with barium oxide. The peroxide forms around 500 °C and oxygen is released above 820 °C. [1] 2 BaO + O 2 ⇌ 2 BaO 2. This reaction is the basis for the now-obsolete Brin process for separating oxygen from the atmosphere. Other oxides, e.g. Na 2 O and SrO, behave similarly. [4]
Barium hydroxide is occasionally used in organic synthesis as a strong base, for example for the hydrolysis of esters [8] and nitriles, [9] [10] [11] and as a base in aldol condensations. There are several uses for barium hydroxide such as to hydrolyse one of the two equivalent ester groups in dimethyl hendecanedioate.
The BaCl species tends to be oxidized to less desirable BaO; barium-containing compositions are therefore usually formulated to be oxygen-deficient. Presence of Ba + is undesired, as it emits in a blue region at 455.4 nm. Potassium may be added to suppress barium ionization, as it ionizes easier and acts as an electron donor for the barium ions ...
Barium peroxide was once used to produce pure oxygen from air. This process relies on the temperature-dependent chemical equilibrium between barium oxide and peroxide: the reaction of barium oxide with air at 500 °C results in barium peroxide, which upon heating to above 700 °C decomposes back to barium oxide with release pure oxygen. [3]
Barium nitrate is manufactured by two processes that start with the main source material for barium, the carbonate. The first involves dissolving barium carbonate in nitric acid, allowing any iron impurities to precipitate, then filtered, evaporated, and crystallized. The second requires combining barium sulfide with nitric acid. [4]