Lithium Oxide Formula: Properties & Sample Questions

Lithium oxide or Lithia (Li₂O) is an inorganic compound formed by the thermal dehydration of lithium hydroxide (LiOH). Lithium metal (from group 1 of the periodic table) binds with oxygen (from group 16) to form lithium oxide. It is a white solid compound with a molecular mass of 29.88g/mol. Lithium metal burns in the presence of oxygen and gets oxidized alongside traces of Lithium peroxides are also formed. In solid-state, lithium oxide is an antifluorite structure. Here we will learn more about the structure and properties of lithium oxide. 

Read Also: Magnesium Bicarbonate

Key Takeaways: Lithium Oxide, Lithium Peroxide, VSEPR theory, Anti fluorite structure, Perovskite structure,

---

Structure of Lithium Oxide

[Click Here for Sample Questions]

Lithium oxide is also known as Kickerite or lithia.

The Ionic formula of lithium oxide is 2[Li+] [O₂−].

It is a strong base. It shows insulation properties, no electrical conductivity. 

Read More: Lewis Dot Structure

In solid-state, lithium oxide adopts an antifluorite structure which is similar to CaF₂, the fluorite structure with Li cation substitutes the fluoride anions while oxide anions are substituted for calcium anion. Besides, the perovskite structured oxides are highly electrically conductive.

Check Important Difference between Cations and Anions

---

Properties of Lithium Oxide

[Click Here for Sample Questions]

Physical Properties

• Lithium oxide has a white crystalline solid with a molar mass of 29.88 g/mol. 
• It has a density of 2.013 g/cm³.
• When in contact with water dissolves quickly and reacts vigorously to form lithium hydroxide (LiOH). But highly insoluble in other solvents.
• The boiling point is 26000C whereas the melting point is 14380C.
• A refractive index of 1.644.

Read More: Unsaturated Solution

Chemical Properties

• Lithium has an antifluorite structure with tetrahedral and cubical coordinate geometry for lithium and oxygen ions respectively.
• In the gas phase, the Li₂O molecule is linear with a bond length consistent with strong ionic bonding. 
• According to valence shell electron pair repulsion theory (VSEPR theory) predicts a bent shape that is similar to H₂O.

Thermodynamic Properties

• Lithium oxide has a heat capacity of 54.1J/mol K.
• The standard molar entropy and the standard enthalpy of formation is 37.88 J/mol K and -595.8 KJ/mol respectively with Gibbs free energy is -562.1 KJ/mol.

Also Read:

---

Preparation and Uses of Lithium Oxide

[Click Here for Sample Questions]

Preparation:

Li₂O is prepared by thermal decomposition of lithium peroxide at 300−400^oC.

• When lithium metal in the air reacts and combines with oxygen, a small amount of lithium peroxide is also formed.

4Li + O₂ → 2Li₂O

• Pure Li2O is prepared by the thermal decomposition of lithium peroxide (Li₂O₂) at 450^oC.

2Li₂O₂ → 2Li₂O + O₂

• Along with these, Lithium nitrate (LiNO₃) is also used for the preparation of Lithium Oxide (Li₂O).

Uses:

• Glazing of Ceramics - Lithium oxide when used with copper exerts blue color and cobalt gives pink color.
• Thermal barrier coating system - Used for the evaluation of non-destructive emission spectroscopy.
• Added as a co-dopant with yttrium oxide which is a white solid and air-stable in nature also known as yttria as a topcoat for ceramic.
• Used as a coolant in nuclear plants
• Used as a thickening agent to bring consistency in greases.

Read More

---

Health Hazards

[Click Here for Sample Questions]

• Very corrosive
• Toxic Fumes
• Respiratory and CNS Effects are seen.

Read More: Carboxyl (-COOH) Groups

---

Things to Remember

[Click Here for Sample Questions]

• Melting and boiling point of lithium oxide is 1438^oC and 2600^oC.
• In antifluorite structure, Li is tetrahedral and Oxygen has a cubical structure.
• The Ionic formula of lithium oxide is 2[Li+] [O₂−].
• According to VSEPR theory, Lithium has a bent shape that is similar to H₂O.
• Li₂O is prepared by thermal decomposition of Lithium peroxide, Lithium nitrate, and combustion of Lithium in the air at high temperatures.
• Used in ceramics, nuclear plants, thermal coating, do-pants in yttrium.

Also Check:

---