What Is Sodium Oxide?
Sodium oxide is a compound formed by mixing sodium with an appropriate amount of oxygen in a chemical reaction.
Under normal conditions, sodium oxide exists in the form of white crystals. It is well soluble in water and changes to sodium hydroxide after dissolution. Sodium oxide reacts violently when exposed to water, so it must be stored and handled with care.
Sodium oxide is generally used in the state of sodium hydroxide after reacting with water.
Uses of Sodium Oxide
Sodium oxide is usually used in the form of sodium hydroxide reacted with water. Sodium hydroxide, also called caustic sodium, is used in a wide range of applications, including synthetic fibers, paper, pulp, chemicals, food industry, and soap.
Otherwise, sodium oxide can absorb carbon dioxide and change to sodium carbonate, or it can be heated in air and change to sodium peroxide. In its stand-alone state, sodium oxide is often used as an ingredient in a variety of compounds.
Properties of Sodium Oxide
Sodium oxide has a melting point of 1,132°C and a decomposition temperature of 1,950°C. When heated above 400°C, sodium oxide decomposes to sodium peroxide (Na2O2) and sodium (Na).
During the weathering of rocks, atmospheric carbon dioxide dissolves into water, which reacts with the sodium oxide in the feldspar contained in the rock, turning it into sodium bicarbonate. Sodium oxide also becomes sodium carbonate when it absorbs carbon dioxide.
Sodium oxide is hygroscopic. Therefore, when sodium oxide is dissolved in water, it reacts violently with water to form sodium hydroxide. When sodium oxide is heated in air, it becomes sodium peroxide.
Structure of Sodium Oxide
Sodium oxide is an inorganic compound that is an oxide of sodium. The chemical formula of sodium oxide is Na2O, its molar mass is 61.979, and its density is 2.27 g/cm3.
Sodium oxide crystals are white crystals belonging to the cubic crystal system. It has an inverted fluorite-type structure, with sodium oxide ions in the position of fluoride ions in calcium fluoride and calcium oxide ions in the position of calcium ions. The lattice constant of sodium oxide is a = 5.55 Å.
Other Information About Sodium Oxide
1. Formation of Sodium Oxide
Sodium oxide can be formed by a chemical reaction involving an appropriate amount of oxygen and sodium. When sodium is heated in excess air, about 20% sodium peroxide is produced as well as sodium oxide.
Relatively pure sodium oxide can be obtained by chemically reacting sodium with sodium hydroxide at 300°C and removing the unreacted sodium using distillation.
In addition, the chemical reaction of liquid sodium with sodium nitrate also produces sodium oxide, along with nitrogen.
2. Other Sodium Oxides
In addition to sodium oxide (Na2O), the composition of sodium oxides includes sodium peroxide (Na2O2) and sodium superoxide (NaO2), both of which contain peroxide ions (O22-).
For example, sodium oxide (Na2O2), also called sodium peroxide, is a yellowish-white granular or powdery substance. Sodium oxide is a strong oxidizing agent that reacts violently with water, breaking it down into hydrogen peroxide and sodium hydroxide. Sodium oxide is therefore also a raw material for the production of hydrogen peroxide.
Sodium superoxide (NaO2), on the other hand, is a superoxide of sodium. It is obtained by reacting sodium oxide with oxygen at high temperature and pressure. Alternatively, sodium superoxide can be obtained by the reaction of an ammonia solution of sodium with oxygen.
Sodium superoxide is easily hydrolyzed to a mixture of sodium peroxide and sodium hydroxide.