Sodium polytungstate

• Sodium dihydrogendodecawolframate
• Hexa - sodium tungstate ( W12 )

White solid

Fixed

3.1 g/cm3 (20 ° C, saturated solution)

Risk

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Sodium polytungstate (also sodium dihydrogendodecawolframate, Eng. Sodium polytungstate, short SPT) is a relatively new agent for the production of a heavy liquid.

Properties

SPT is a solid-state white, crystalline powder or in aqueous solution, a slightly yellow-green transparent liquid. In its crystalline form, it is a 12-fold aggregated Isopolywolframat with a molecular mass of 2986.12 g · mol -1. The models according to the polytungstate is constructed from octahedrons, wherein there are the oxygen ions at the corners, and the tungsten ions in the center of the octahedron. In the illustration as a sphere model, the oxygen ions form a close packing of spheres, the tungsten ions are located in the octahedral sites. The structure as it is in this connection a so-called "real" dihydrogendodecawolframate having the formula Na6 [ H2W12O40 ]. From the real metatungstates is known that the two hydrogen atoms are present in the central cavity of the polyanion and the ball cup can not pass through.

Use

Due to its extremely high solubility in water (max. density to 3.1 g/cm3), it is suitable as a heavy liquid. Compared to a ätzendenen zinc chloride solution or the toxic halocarbons it despite the higher price advantages in the sink-float analysis or density gradient centrifugation.

SPT is non-toxic, non-flammable, odorless and in addition it has a very low viscosity as a solution, but the solutions of high concentration have been relatively high viscosities.