LABORATORY CHEMICAL SAFETY SUMMARY: POTASSIUM HYDRIDE AND SODIUM HYDRIDE

Substance

Potassium hydride

CAS 7693-26-7

Sodium hydride

CAS 7646-69-7

 

(Commonly handled as dispersions in mineral oil)

Formula

KH; NaH

 

Physical Properties

White to brownish-gray crystalline powders (white-gray or white-beige dispersion in mineral oil)

NaH: mp 800 °C (decomposes)

Reacts violently with water

 

Autoignition Temperature

Ignites spontaneously at room temperature in moist air

 

Major Hazards

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

 

Toxicity

Sodium hydride and potassium hydride react with the moisture on skin and other tissues to form highly corrosive sodium and potassium hydroxide. Contact of these hydrides with the skin, eyes, or mucous membranes causes severe burns; thermal burns may also occur due to ignition of the liberated hydrogen gas.

 

Flammability and Explosibility

Potassium hydride and sodium hydride are flammable solids that ignite on contact with moist air. Potassium hydride presents a more serious fire hazard than sodium hydride. The mineral oil dispersions do not ignite spontaneously on exposure to the atmosphere. Sodium hydride and potassium hydride 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 CO2extinguishers must never be used on sodium and potassium hydride fires.

 

Reactivity and Incompatibility

Potassium hydride and sodium hydride react violently with water, liberating hydrogen, which can ignite. Oil dispersions of these hydrides are much safer to handle because the mineral oil serves as a barrier to moisture and air. Potassium hydride may react violently with oxygen, CO, dimethyl sulfoxide, alcohols, and acids. Explosions can result from contact of these compounds with strong oxidizers. Potassium hydride is generally more reactive than sodium hydride.

 

Storage and Handling

Sodium hydride and potassium hydride 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 highly reactive (Chapter 5.G) substances. Safety glasses, impermeable gloves, and a fire-retardant laboratory coat should be worn at all times when working with these substances. These hydrides should be used only in areas free of ignition sources and should be stored preferably as mineral oil dispersions under an inert gas such as argon.

 



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement