Lithium hydroxide

Lithium hydroxide (LiOH) is a corrosive alkali hydroxide. It is a white hygroscopic crystalline material. It is soluble in water, and slightly soluble in ethanol. It is available commercially in anhydrous form, or as the monohydrate.

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Applications

Lithium hydroxide is used in carbon dioxide scrubbers for purification of gases and air. It is used as a heat transfer medium, as a storage-battery electrolyte, and as a catalyst for polymerization. It is also used in ceramics, manufacturing other lithium compounds, and esterification specially for lithium stearate (which is used as a general purpose lubricating grease due to its high resistance to water and is useful at both high and low temperatures).

Production

Lithium hydroxide can be produced by dissolving lithium or lithium oxide in water. The reaction is as follows:

2 Li + 2 H₂O → 2 LiOH + H₂

Li₂O + H₂O → 2 LiOH

Because lithium reacts rapidly (but not violently) with water, lithium batteries should be kept away from water.

Industrially, lithium hydroxide is produced in a metathesis reaction between lithium carbonate and calcium hydroxide:

Li₂CO₃ + Ca(OH)₂ → LiOH + CaCO₃

Reactions

Lithium hydroxide is used in breathing gas purification systems for spacecraft (Lithium hydroxide canisters in the LEM were lifelines for the Apollo 13 astronauts), submarines, and rebreathers to remove carbon dioxide from exhaled gas by producing lithium carbonate and water:

2 LiOH·H₂O + CO₂ → Li₂CO₃ + 3 H₂O

Or,

2 LiOH + CO₂ → Li₂CO₃ + H₂O

The later, anhydrous hydroxide is preferred for its lower mass and lesser water production for respirator systems in spacecraft. 1 gram of anhydrous lithium hydroxide can remove 450 cm³ of carbon dioxide gas. The monohydrate loses its water at 100-110 °C.

See also

• soda lime