Sodium oxide is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with the formula . It is used in

ceramic A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcela ...

s and

glass Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window pane ...

es. It is a white solid but the compound is rarely encountered. Instead "sodium oxide" is used to describe components of various materials such as glasses and fertilizers which contain oxides that include sodium and other elements. Sodium oxide is a component.

Structure

The structure of sodium oxide has been determined by

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

. Most alkali metal oxides (M = Li, Na, K, Rb) crystallise in the antifluorite structure. In this motif the positions of the

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

s and

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

s are reversed relative to their positions in , with

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

ions tetrahedrally coordinated to 4 oxide ions and oxide cubically coordinated to 8 sodium ions.

Preparation

Sodium oxide is produced by the reaction of

with

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), ...

, sodium peroxide, or sodium nitrite: : To the extent that NaOH is contaminated with water, correspondingly greater amounts of sodium are employed. Excess sodium is distilled from the crude product. A second method involves heating a mixture of sodium azide and

sodium nitrate Sodium nitrate is the chemical compound with the chemical formula, formula . This alkali metal nitrate salt (chemistry), salt is also known as Chile saltpeter (large deposits of which were historically mined in Chile) to distinguish it from ordi ...

: : Burning sodium in air produces a mixture of and sodium peroxide (). A third much less known method involves heating sodium metal with

iron(III) oxide Iron(III) oxide or ferric oxide is the inorganic compound with the formula . It occurs in nature as the mineral hematite, which serves as the primary source of iron for the steel industry. It is also known as red iron oxide, especially when use ...

(rust): : the reaction should be done in an inert atmosphere to avoid the reaction of sodium with the air instead.

Applications

Glassmaking

Glasses are often described in terms of their sodium oxide content although they do not really contain . Furthermore, such glasses are not made from sodium oxide, but the equivalent of is added in the form of "soda" ( sodium carbonate), which loses

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

at high temperatures: : : : A typical manufactured

contains around 15% sodium oxide, 70% silica (

silicon dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundan ...

), and 9% lime ( calcium oxide). The sodium carbonate "soda" serves as a flux to lower the temperature at which the silica mixture melts. Such soda-lime glass has a much lower melting temperature than pure silica and has slightly higher elasticity. These changes arise because the -based material is somewhat more flexible.

Reactions

Sodium oxide reacts readily and irreversibly with water to give

: : Because of this reaction, sodium oxide is sometimes referred to as the base anhydride of sodium hydroxide (more archaically, "anhydride of caustic soda").

References

{{oxygen compounds Oxides Sodium compounds Fluorite crystal structure