Lithium hydroxide

Lithium hydroxide
IUPAC name	Lithium hydroxide
Other names	Lithine
Identifiers
CAS number	1310-65-2 Y, 1310-66-3 (monohydrate)
PubChem	3939
UN number	2680
RTECS number	OJ6307070
Properties
Molecular formula	LiOH
Molar mass	23.95 g/mol
Appearance	hygroscopic white solid odorless
Density	1.46 g/cm3 (anhydrous) 1.51 g/cm3 (monohydrate)
Melting point	462 °C
Boiling point	924 °C decomp.
Solubility in water	anhydrous: 12.8 g/100 mL (20 °C) 12.5 g/100 mL (25 °C) 17.5 g/100 mL (100 °C) monohydrate: 22.3 g/100 mL (10 °C) 26.8 g/100 mL (100 °C) [1]
Refractive index (nD)	1.464 (anhydrous) 1.460 (monohydrate)
Thermochemistry
Std enthalpy of formation ΔfHo298	-20.36 kJ/g
Specific heat capacity, C	2.071 J/g K
Hazards
MSDS	ICSC 0913 ICSC 0914 (monohydrate)
EU Index	Not listed
Main hazards	Corrosive
NFPA 704	0 3 0
Flash point	Non-flammable
Related compounds
Other anions	Lithium amide
Other cations	Sodium hydroxide Potassium hydroxide Rubidium hydroxide Caesium hydroxide
Related compounds	Lithium oxide
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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.

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

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

LiOH_(aq) is a strong base.

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 → 2LiOH + CaCO₃

Reactions

Lithium hydroxide is used in breathing gas purification systems for spacecraft (Lithium hydroxide canisters in the LM and CM (after modification) were lifelines for the Apollo 13 astronauts), submarines, and rebreathers to remove carbon dioxide from exhaled gas by producing lithium carbonate and water:^[2]

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. 1 gram of anhydrous lithium hydroxide can remove 450 cm³ of carbon dioxide gas. The monohydrate loses its water at 100-110 °C.

LiOH_(aq) + HF → LiF + H₂O.

LiF shows basic nature, so it changes the red litmus paper into blue.

See also

• soda lime

References

External links

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