Editing Barium hydroxide (section)

==Preparation and structure==
Barium hydroxide can be prepared by dissolving [[barium oxide]] (BaO) in [[water]]:

:BaO + H<sub>2</sub>O → Ba(OH)<sub>2</sub>

It crystallises as the octahydrate, which converts to the monohydrate upon heating in air.  At  100&nbsp;°C in a vacuum, the monohydrate will yield BaO and water.<ref>(1960). ''Gmelins Handbuch der anorganischen Chemie (8. Aufl.)'', Weinheim: Verlag Chemie, p. 289.</ref>  The monohydrate adopts a layered structure (see picture above).  The Ba<sup>2+</sup> centers adopt a [[Square antiprismatic molecular geometry|square antiprismatic geometry]].  Each Ba<sup>2+</sup> center is bound by two water [[ligand]]s and six hydroxide ligands, which are respectively doubly and triply bridging to neighboring Ba<sup>2+</sup> centre sites.<ref>Kuske, P.; Engelen, B.; Henning, J.; Lutz, H.D.; Fuess, H.; Gregson, D. "Neutron diffraction study of Sr(OH)<sub>2</sub>(H<sub>2</sub>O) and beta-Ba(OH)<sub>2</sub>*(H<sub>2</sub>O)" Zeitschrift für Kristallographie (1979-2010) 1988, vol. 183, p319-p325.</ref>  In the octahydrate, the individual Ba<sup>2+</sup> centers are again eight coordinate but do not share ligands.<ref>Manohar, H.; Ramaseshan, S. "The crystal structure of barium hydroxide octahydrate Ba (OH)<sub>2</sub>(H<sub>2</sub>O)<sub>8</sub>" Zeitschrift für Kristallographie, Kristallgeometrie, Kristallphysik, Kristallchemie 1964. vol. 119, p357-p374</ref>
[[File:Ba(OH)2O2HCoordSph.tif|thumb|left|Coordination sphere about an individual barium ion in Ba(OH)<sub>2</sub>.H<sub>2</sub>O.]]