Lithium oxide

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Lithium oxide
Lithium-oxide-unit-cell-3D-balls-B.png
Identifiers
CAS number 12057-24-8 YesY
PubChem 166630
ChemSpider 145811 YesY
RTECS number OJ6360000
Jmol-3D images Image 1
Properties
Molecular formula Li
2
O
Molar mass 29.88 g/mol
Appearance white solid
Density 2.013 g/cm3
Melting point 1,438 °C (2,620 °F; 1,711 K)
Boiling point 2,600 °C (4,710 °F; 2,870 K)
Solubility in water reacts violently to form LiOH
log P 9.23
Refractive index (nD) 1.644 [1]
Structure
Crystal structure Antifluorite (cubic), cF12
Space group Fm3m, No. 225
Coordination
geometry
Tetrahedral (Li+); cubic (O2–)
Thermochemistry
Specific
heat capacity
C
1.8105 J/g K or 54.1 J/mol K
Std molar
entropy
So298
37.89 J/mol K
Std enthalpy of
formation
ΔfHo298
-20.01 kJ/g or -595.8 kJ/mol
Gibbs free energy ΔG -562.1 kJ/mol
Hazards
EU Index Not listed
Main hazards Corrosive, reacts violently with water
Flash point Non-flammable
Related compounds
Other anions Lithium sulfide
Other cations Sodium oxide
Potassium oxide
Rubidium oxide
Caesium oxide
Related lithium oxides Lithium peroxide
Lithium superoxide
Related compounds Lithium hydroxide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Lithium oxide (Li
2
O) or lithia is an inorganic chemical compound. Lithium oxide is formed along with small amounts of lithium peroxide when lithium metal is burned in the air and combines with oxygen:[2]

4Li + O
2
→ 2Li
2
O
.

Pure Li
2
O
can be produced by the thermal decomposition of lithium peroxide, Li
2
O
2
, at 450 °C[2]

2Li
2
O
2
→ 2Li
2
O
+ O
2

Structure[edit]

In the solid state lithium oxide (also known as dilithium monoxide) adopts an antifluorite structure which is related to the CaF
2
, fluorite structure with Li cations substituted for fluoride anions and oxide anions substituted for calcium cations.[3] The ground state gas phase Li
2
O
molecule is linear with a bond length consistent with strong ionic bonding.[4][5] VSEPR theory would predict a bent shape similar to H
2
O
.

Uses[edit]

Lithium oxide is used as a flux in ceramic glazes; and creates blues with copper and pinks with cobalt. Lithium oxide reacts with water and steam, forming lithium hydroxide and should be isolated from them.

Its usage is also being investigated for non-destructive emission spectroscopy evaluation and degradation monitoring within thermal barrier coating systems. It can be added as a co-dopant with yttria in the zirconia ceramic top coat, without a large decrease in expected service life of the coating. At high heat, lithium oxide emits a very detectable spectral pattern, which increases in intensity along with degradation of the coating. Implementation would allow in situ monitoring of such systems, enabling an efficient means to predict lifetime until failure or necessary maintenance.

See also[edit]

References[edit]

  1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  2. ^ a b Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. pp. 97–99. ISBN 0-08-022057-6. 
  3. ^ Zintl, E.]]; Harder, A.; Dauth B. (1934). "Gitterstruktur der oxyde, sulfide, selenide und telluride des lithiums, natriums und kaliums". Zeitschrift für Elektrochemie und Angewandte Physikalische Chemie 40: 588–93. 
  4. ^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
  5. ^ A spectroscopic determination of the bond length of the LiOLi molecule: Strong ionic bonding, D. Bellert, W. H. Breckenridge, J. Chem. Phys. 114, 2871 (2001); doi:10.1063/1.1349424

External links[edit]