Strontium Tungstates

The anhydrous normal salt, SrWO₄, is precipitated on the addition of strontium acetate solution to a solution of a normal alkali tungstate, or it may be obtained in the crystalline form by fusing together strontium chloride, sodium tungstate, and sodium chloride. The crystals are white, translucent, tetragonal bipyramids, a:c = 1:1.5582, and of density 6.184.

Strontium ditungstate, SrO.2WO₃.3H₂O, is described by Lefort as a white precipitate formed by the addition of strontium acetate to sodium ditungstate solution. It is only slightly soluble in water and becomes anhydrous on heating.

Strontium paratungstate, 3SrO.7WO₃.16H₂O, is precipitated on adding a hot solution of a paratungstate to a hot solution of strontium chloride or nitrate, using excess of the strontium salt. It is a granular crystalline powder, which does not fuse at red heat. The double salt, Na₂O.4SrO.12WO₃.29H₂O, is obtained by adding a strontium salt to a boiling solution of sodium paratungstate until the precipitate no longer redissolves; on filtering and allowing the solution to crystallise, white scales separate. The salt on heating turns yellow but does not fuse.

The salt, 4SrO.10WO₃.26H₂O, is a white insoluble granular powder obtained in the same way as the corresponding barium and calcium salts. Strontium tritungstate, SrO.3WO₃.5H₂O, is described by Lefort.