The anhydrous selenide is a very unstable compound obtained by the action of hydrogen on lithium selenate. A hydrated form, Li2Se,9H2O, was obtained by Fabre in colourless crystals by passing hydrogen selenide through a concentrated aqueous solution of lithium hydroxide in absence of air. It retains its water of crystallization tenaciously. The heat of formation of the anhydrous compound from its elements is given by the equation
2[Li] + [Se](cryst.)=[Li2Se]+88.l Cal. |