Substance

Sodium

(Natrium)

CAS 7440-23-5

Formula

Na

Physical Properties

Soft, silvery-white metal

bp 881.4 °C, mp 97.8 °C

Reacts violently with water

Vapor Pressure

1.2 mmHg at 400 °C

Autoignition Temperature

>115 °C in air

Major Hazards

Reacts violently with water, liberating highly flammable hydrogen gas; causes severe burns on eye or skin contact.

Toxicity

Sodium reacts with the moisture on skin and other tissues to form highly corrosive sodium hydroxide. Contact of metallic sodium with the skin, eyes, or mucous membranes causes severe burns; thermal burns may also occur due to ignition of the metal and liberated hydrogen.

Flammability an Explosibility d

Sodium spontaneously ignites when heated above 115 °C in air that has even modest moisture content, and any sodium vapor generated is even more flammable. Sodium reacts violently on contact with water and often ignites or explodes the hydrogen formed. Sodium fires must be extinguished with a class D dry chemical extinguisher or by the use of sand, ground limestone, dry clay or graphite, or ''Met-L-X ^®" type solids. Water or CO₂ extinguishers must never be used on sodium fires.

Reactivity and Incompatibility

Sodium is a potent reducing agent and reacts violently with water to form hydrogen and sodium hydroxide. It also reacts violently with mineral acids and halogens and reacts exothermically with oxidizing agents, organic and inorganic halides, and protic media. Shock-sensitive mixtures can form upon reaction of sodium with halogenated hydrocarbons such as carbon tetrachloride and chloroform. Sodium also reacts to generate shock-sensitive products with sulfur oxides and phosphorus, and reacts with incandescence with many metal oxides such as mercurous and lead oxides. Sodium dissolves in many other metals such as mercury and potassium with great evolution of heat. The reactivity of a sample of sodium is largely related to its surface area. Thus, reactions involving large pieces of sodium metal (especially those with some oxide or hydroxide coating) may be slow and controlled, but similar reactions involving clean, high-surface-area sodium dispersions may be vigorous or violent.

Storage and Handling

Sodium should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C, supplemented by the additional precautions for work with flammable