Lithium hydroxide


Lithium hydroxide is an inorganic compound with the formula LiOH. It is a white hygroscopic crystalline material. It is soluble in water and slightly soluble in ethanol, and is available commercially in anhydrous form and as the monohydrate. While lithium hydroxide is a strong base, it is the weakest known alkali metal hydroxide.

Production and reactions

Lithium hydroxide is produced in a metathesis reaction between lithium carbonate and calcium hydroxide:
The initially produced hydrate is dehydrated by heating under vacuum up to 180 °C.
In the laboratory, lithium hydroxide arises by the action of water on lithium or lithium oxide. The equations for these processes follow:
Typically, these reactions are avoided.
Although lithium carbonate is more widely used, the hydroxide is an effective precursor to lithium salts, e.g.

Gas phase chemistry

The acidity of LiOH has been measured in the gas phase. The oxidolithium anion, LiO–, was produced by successive decarboxylation and decarbonylation of monolithium oxalate anion, LiOO–, by collision-induced dissociation and was identified by its exact mass. The gas-phase acidity of LiOH was inferred from the experimentally determined electron affinity of LiO• and previously known heats of formation to give a value of 426 ± 2 kcal/mol. This is considerably higher than the gas-phase acidity of water and even exceeds that of methane. Thus, LiOH is a very weak acid and is in fact the weakest acid yet measured in the gas phase.

Applications

Lithium hydroxide is mainly consumed in the production of lithium greases. A popular lithium grease thickener is Lithium 12-hydroxystearate, which produces a general-purpose lubricating grease due to its high resistance to water and usefulness at a range of temperatures.

Carbon dioxide scrubbing

Lithium hydroxide is used in breathing gas purification systems for spacecraft, submarines, and rebreathers to remove carbon dioxide from exhaled gas by producing lithium carbonate and water:
or
The latter, anhydrous hydroxide, is preferred for its lower mass and lesser water production for respirator systems in spacecraft. One gram of anhydrous lithium hydroxide can remove 450 cm3 of carbon dioxide gas. The monohydrate loses its water at 100–110 °C.

Other uses

It is used as a heat transfer medium and as a storage-battery electrolyte. It is also used in ceramics and some Portland cement formulations. Lithium hydroxide is used to alkalize the reactor coolant in pressurized water reactors for corrosion control.

Market

In 2012, the price of lithium hydroxide was about $5,000 to $6,000 per tonne.