Chemical Properties of Barium
Barium may be kept unchanged in dry carbon dioxide, but readily tarnishes in the air owing to the formation of the oxide and nitride. If in the form of powder it may even take fire. It decomposes both water and alcohol, liberating hydrogen, but is unattacked by dry benzene, toluene, and petrol. It combines with ammonia and also with hydrogen. Its behaviour to most reagents is similar to that of calcium and strontium.
The conditions have been studied under which barium, amalgamated with mercury, may be replaced by potassium or sodium from salt solutions in contact with it.
Compounds of Barrium
In common with the other alkaline earths, barium behaves generally as a divalent element. In its salts it forms a colourless divalent ion. Abel observed a catalytic effect produced by the barium ion in certain oxidation processes, such as the oxidation of sodium thiosulphate by hydrogen peroxide, and ascribed this to the formation of a quadrivalent barium ion. It seemed probable that calcium and strontium behave similarly.
Certain acids are frequently prepared by treating the barium salts with sulphuric or phosphoric acid.
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