Properties of sodium

Sodium is silvery-white, lustrous metal. It is soft and can be cut with a knife or scissors. It has lower density than water and low melting point. Sodium is a very reactive metal. It is stored under liquid paraffin or kerosene to prevent its contact from air or moisture. It tarnishes in air rapidly due to the formation of an oxide layer on its surface.

Sodium reacts with water vigorously to form sodium hydroxide (basic solution) and hydrogen gas according to the following equation.

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)

When sodium is exposed to air, it unites with oxygen to form sodium peroxide. If sodium metal is reacted with excess oxygen some sodium oxide is formed. The equations for the reactions are as follows

2Na + O₂ → Na₂O₂(Sodium peroxide)

4Na + O₂ → Na₂O(Sodium peroxide)

Uses of sodium

Sodium metal is used to make sodium peroxide, Na₂O₂ (used in bleaching), sodium cyanide, NaCN(used for gold and silver extraction) and sodium amide, NaNH₂ (used to make dyes). Sodium is also used to make sodium vapor lamps that are responsible for the orange-yellowish lights on most highways in cities. It is also used to cool the fuel in nuclear reactors due to its high heat conductivity.

Uses of sodium compounds

Sodium chloride (NaCl): It is a white crystalline solid that is water soluble, it is used:

• as table salt in food preparation and preservation.
• as raw material in the manufacturing of sodium hydroxide, sodium metal, chlorine gas, sodium carbonate, sodium bicarbonate and hydrochloric acid.
• in medicine as component of Oral Rehydration Salt (ORS).

Sodium hydroxide (NaOH): It is also called caustic soda or lye. It is a white brittle solid, very soluble in water. It is used:

• in the production of soaps and detergents.
• in the purification of petroleum products.
• in the manufacturing of artificial silk, rayon.
• in the manufacturing of paper and pulp.
• in textile production.
• as a drying agent in chemical industries due to its capacity of absorbing water.

Sodium carbonate, Sodium trioxocarbonate (IV) (Na₂CO₃): It is also called soda ash in the form of Sodium trioxocarbonate (IV). Sodium carbonate is generally used:

• in manufacturing glass, soap, paper, leather and sodium hydroxide.
• in cleaning, in water softening , in petroleum refining and in dyeing.

Sodium bicarbonate (NaHCO₃): It is also known as sodium hydrogen carbonate, sodium hydrogen trioxocarbonate (IV) and is commonly called baking soda. It is a white powder that is water soluble. Sodium bicarbonate is used:

• to make baking powder.
• as a source of carbon dioxide gas in fire extinguishers.
• to manufacture sodium carbonate.

Sodium Nitrate (NaNO₃): It is also called sodium trioxonitrate(V) commonly called, Chile saltpeter. It is a white crystalline solid and very soluble in water. It is used:

• as a fertilizer .
• in the production of nitric acid and other nitrates.
• as meat preservative in former times.

Sodium Chlorate (NaClO₃): It is also called sodium trioxochlorate(V), it is a white solid soluble in water. It is used:

• as an oxidizing agent in chemical processes due to its capacity to generate oxygen on heating.
• in manufacturing explosives, to make match boxes.
• as a weed killer in agriculture and the textile industry.