Barium hydroxide, \(Ba(OH)_2\), is also known as baryta. It can be prepared either by dissolving barium oxide (\(BaO\)) or barium sulfide (\(BaS\)) in water:
\[BaO + H_2O \rightarrow Ba(OH)_2 + H_2O\]
\[BaS + H_2O \rightarrow Ba(OH)_2 + H_2S\]
Barium hydroxide crystallizes as the octahydrate, \(Ba(OH)_2 \cdot 8H_2O\), which can be converted to the monohydrate by heating in air. The white granular monohydrate is the usual commercially available form. Barium hydroxide decomposes to barium oxide when heated to 800°C.
Barium hydroxide forms an alkaline solution in water ("baryta water") which can be used to titrate weak acids, since its clear aqueous solution is guaranteed to be free of carbonate (barium carbonate is insoluble in water).
- Hans Lohninger (Epina eBook Team)