Title: Cobaltous Oxide
CAS Registry Number: 1307-96-6
Molecular Formula: CoO
Molecular Weight: 74.93
Percent Composition: Co 78.65%, O 21.35%
Literature References: Prepn: Amiel et al., Compt. Rend. 259, 3512 (1964); Wilke, Z. Anorg. Allg. Chem. 330, 164 (1964). Toxicity study: Smyth et al., Am. Ind. Hyg. Assoc. J. 30, 470 (1969). Review: de Bie, Doyen, Cobalt 15, 3-13; 16, 3-15 (1962).
Properties: Powder, or cubic or hexagonal crystals. Color varies from olive green to red, depending on the particle size, but the commercial material is usually dark grey and contains about 76% Co. mp ~1935°. d 5.7 to 6.7, depending on method of prepn. Readily absorbs O2 even at room temp. Practically insol in water. Sol in acids or alkalies. Easily reduced to Co by C or CO. Reacts at high temperatures with silica, alumina, zinc oxide to form pigments. LD50 orally in rats: 1.70 g/kg (Smyth).
Melting point: mp ~1935°
Density: d 5.7 to 6.7
Toxicity data: LD50 orally in rats: 1.70 g/kg (Smyth)
NOTE: The commercial oxides are usually not definite chemical compds but mixtures of the cobalt oxides.
Use: In pigments for ceramics; glass coloring and decolorization; oxidation catalyst for drying oils, fast-drying paints and varnishes; prepn of cobalt-metal catalysts, Co powder for binder in sintered tungsten carbide; in semiconductors. |