Lithium hydroxide

Lithium hydroxide

Names
IUPAC name Lithium hydroxide
Other names Lithine
Identifiers
CAS Number	1310-65-2 Y 1310-66-3 (monohydrate) N
ChEBI	CHEBI:33979 Y
ChemSpider	3802 Y
Jmol 3D model	Interactive image
PubChem	3939
RTECS number	OJ6307070
UNII	903YL31JAS Y
UN number	2680
InChI InChI=1S/Li.H2O/h;1H2/q+1;/p-1 Y Key: WMFOQBRAJBCJND-UHFFFAOYSA-M Y InChI=1/Li.H2O/h;1H2/q+1;/p-1 Key: WMFOQBRAJBCJND-REWHXWOFAT
SMILES [Li+].[OH-]
Properties
Chemical formula	LiOH
Molar mass	23.95 g/mol (anhydrous) 41.96 g/mol (monohydrate)
Appearance	hygroscopic white solid odorless
Density	1.46 g/cm3 (anhydrous) 1.51 g/cm3 (monohydrate)
Melting point	462 °C (864 °F; 735 K)
Boiling point	924 °C (1,695 °F; 1,197 K) decomposes
Solubility in water	anhydrous: 12.7 g/100 mL (0 °C) 12.8 g/100 mL (20 °C) 17.5 g/100 mL (100 °C) monohydrate: 22.3 g/100 mL (10 °C) 26.8 g/100 mL (80 °C)
Solubility in methanol	anhydrous: 9.76 g/100 g (20 °C, 48 hours mixing) monohydrate: 13.69 g/100 g (20 °C, 48 hours mixing)
Solubility in ethanol	anhydrous: 2.36 g/100 g (20 °C, 48 hours mixing) monohydrate: 2.18 g/100 g (20 °C, 48 hours mixing)
Solubility in isopropanol	anhydrous: 0 g/100 g (20 °C, 48 hours mixing) monohydrate: 0.11 g/100 g (20 °C, 48 hours mixing)
Basicity (pKb)	-0.63
Refractive index (nD)	1.464 (anhydrous) 1.460 (monohydrate)
Thermochemistry
Specific heat capacity (C)	2.071 J/g K
Std enthalpy of formation (ΔfHo298)	-20.36 kJ/g
Vapor pressure	{{{value}}}
Related compounds
Other anions	Lithium amide
Other cations	Sodium hydroxide Potassium hydroxide Rubidium hydroxide Caesium hydroxide
Related compounds	Lithium oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

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 the weakest base among the alkali metal hydroxides. It is available commercially in anhydrous form and as the monohydrate (LiOH^.H₂O), both of which are strong bases.

Production and reactions

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

Li₂CO₃ + Ca(OH)₂ → 2 LiOH + CaCO₃

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:

2 Li + 2 H₂O → 2 LiOH + H₂

Li₂O + H₂O → 2 LiOH

Typically, these reactions are avoided.

Although lithium carbonate is more widely used, the hydroxide is an effective precursor to lithium salts, e.g.

LiOH + HF → LiF + H₂O.

Applications

Lithium hydroxide is mainly consumed for the production of lithium greases. A popular lithium grease is lithium stearate, which is a general-purpose lubricating grease due to its high resistance to water and usefulness at both high and low temperatures.

Carbon dioxide scrubbing

Further information: carbon dioxide scrubber

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:

2 LiOH·H₂O + CO₂ → Li₂CO₃ + 3 H₂O

Or,

2LiOH + CO₂ → Li₂CO₃ + H₂O

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 (isotopically enriched in lithium-7) is used to alkalize the reactor coolant in pressurized water reactors for corrosion control.

See also

• Soda lime

External links

• International Chemical Safety Card 0913 (anhydrous)
• International Chemical Safety Card 0914 (monohydrate)