Sodium metatungstate

Sodium metatungstate is the inorganic compound with the formula Na6[H2W12O40], sometimes written 3Na2WO4·9WO3·H2O.

The anion is the polyoxotungstate [H2W12O40]6-, which features six-coordinated tungsten(VI) centers interconnected with doubly- and triply bridging oxo ligands.

density 3.1 g/cm3), SPT is widely used as to produce "heavy liquid" for gravity separation (sink /float analysis) and density gradient centrifugation.

It has significant advantages when compared to zinc chloride solution or the toxic halogenated carbons for sink-swim analysis.

Aqueous SPT is non-toxic (unlike the denser Clerici solution), non-flammable, odorless, reusable and additionally it has a low viscosity.

The [W 12 O 40 ] 8- cage. Metatungstates feature the doubly protonated derivative of this cage, i.e. [H 2 W 12 O 40 ] 6- . [ 1 ]