Agent Name

CARBIDES

Alternative Name

CLASS

Major Category

Metals

Synonyms

CLASSES

Category

Metals, Inorganic Compounds

Sources/Uses

Calcium carbide is a source of acetylene; Other carbides (silicon, tungsten, tantalum, etc.) are valued for their extreme hardness and chemical inertness; [www.britannica.com]

Comments

Carbides are one of the four binary salts that have specific hazards (nitrides, carbides, hydrides, and phosphides); Carbides give off acetylene, and a corrosive base is formed from contact with water. The corrosive base is the hydroxide of the metal that is attached to the carbon in the carbide compounds. On contact with water, calcium carbide produces acetylene and the corrosive calcium hydroxide. [Burke, p. 21] Most of the ionic carbides are acetylides, that is, they form acetylene, but beryllium carbide and aluminum carbide form methane. Acetylides include those of the alkali metals (Li, Na, K, Rb, Cs, and Fr) and alkaline-earth metals (Mg, Ca, Sr, Ba, and Ra) plus lanthanum, copper, silver, gold, zinc, cadmium, and mercury. "In contrast to the ionic carbides, most interstitial carbides do not react with water and are chemically inert." [www.britannica.com] "The saltlike carbides--also called ionic carbides--are attacked by water to form hydrocarbons. Most of these carbides form acetylene . . . Metal-like carbides of metallic elements are the carbides of the transition elements of groups 4, 5, and 6 of the periodic table. These carbides, also called metallic carbides, are not attacked by water. . . . The carbides of Mn, Fe, Co, and Ni are generally included in the metal-like carbides, although they are really better classified as a group on their own. . . . The pure compounds [carbides of Mn, Fe, Co, and Ni] are attacked by water or dilute acids." [Ullmann: Carbides]

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