Lithium tungstate is the
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
with the formula Li
2WO
4. It is a white solid that is soluble in water. The compound is one of the several ortho
tungstates, compounds that feature the tetrahedral WO
42− anion.
Structure
The
salt consists of tetrahedrally coordinated Li and W centres bridged by oxides. The W-O and Li-O
bond distance
In molecular geometry, bond length or bond distance is defined as the average distance between nuclei of two bonded atoms in a molecule. It is a transferable property of a bond between atoms of fixed types, relatively independent of the rest of ...
s are 1.79 and 1.96 Å, respectively. These differing bond lengths reflect the multiple bond character of the W-O interaction and the weaker ionic bonding between the Li-O interactions. The solid undergoes
phase transitions at high pressures, such that the coordination geometry at tungsten becomes octahedral (six W-O bonds). For example at 40 kilobars, it adopts a structure related to
wolframite.
Uses
Lithium tungstate is used to produce high density aqueous polytungstate (metatungstate) solutions. Like other high density fluids, such solutions are often used in the separation of minerals and other solids. These can achieve a density of 2.95 at 25°C and up to 3.6 in hot water.
This use of lithium and sodium tungstate anions was developed in the 1980s and early 1990s to address toxicity and safety issues with the existing organic high density fluids. Unlike
methylene iodide and
bromoform, polytungstates and heteropolytungstates can be more safely be used in an indoor environment without a fume hood with only ordinary common sense safety precautions such as protective gloves and safety glasses.
[MSDS and safety information]
References
{{tungsten compounds
Tungstates
Lithium salts