SODIUM

Sodium
(Natrium)
CAS 7440-23-5

Na

Soft, silvery-white metal
bp 881.4 °C, mp 97.8 °C
Reacts violently with water

1.2 mmHg at 400 °C

>115 °C in air

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

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.

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.

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.

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 (Chapter 5.F) and reactive (Chapter 5.G) substances. Safety glasses, impermeable gloves, and a fire-retardant laboratory coat should be worn at all times when working with sodium, and the metal should be handled under the surface of an inert liquid such as mineral oil, xylene, or toluene. Sodium should be used only in areas free of ignition sources and should be stored under mineral oil in tightly sealed metal containers under an inert gas such as argon.

In the event of skin contact, immediately remove contaminated clothing and any metal particles and wash with soap and water. In case of eye contact, promptly wash with copious amounts of water for 15 min (lifting upper and lower lids occasionally) and obtain medical attention. If sodium is ingested, obtain medical attention immediately.

In the event of a spill, remove all ignition sources, cover the sodium with a dry chemical extinguishing agent, sweep up, place in an appropriate container under an inert atmosphere, and dispose of properly. Respiratory protection may be necessary in the event of a spill or release in a confined area.

Excess sodium and waste material containing this substance can be placed in an appropriate container under an inert atmosphere, clearly labeled, and handled according to your institution's waste disposal guidelines. Experienced personnel can destroy small scraps of sodium by carefully adding 95% ethanol to a beaker containing the metal scraps covered in an inert solvent such as xylene or toluene. The resulting mixture should then be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines.

The information in this LCSS has been compiled by a committee of the National Research Council from literature sources and Material Safety Data Sheets and is believed to be accurate as of July 1994. This summary is intended for use by trained laboratory personnel in conjunction with the NRC report Prudent Practices in the Laboratory: Handling and Disposal of Chemicals. This LCSS presents a concise summary of safety information that should be adequate for most laboratory uses of the title substance, but in some cases it may be advisable to consult more comprehensive references. This information should not be used as a guide to the nonlaboratory use of this chemical.

Copyright 1995 National Academy of Sciences. All rights reserved.