Title: Chromium(III) Oxide
CAS Registry Number: 1308-38-9
CAS Name: Chromium oxide (Cr2O3)
Additional Names: anadonis green; chrome green; chrome ocher; chrome oxide green; chromia; chromic oxide; chromium sesquioxide; green cinnabar; green oxide of chromium; green rouge; leaf green; oil green; ultramarine green; C.I. Pigment Green 17; C.I. 77288
Molecular Formula: Cr2O3
Molecular Weight: 151.99
Percent Composition: Cr 68.42%, O 31.58%
Literature References: Prepd by reaction of sodium dichromate or chromate with sulfur: Copson in ACS Monograph Series no. 132, entitled "Chromium," vol. 1, M. J. Udy, Ed. (Reinhold, New York, 1956) pp 277-278. Review: Wiesburg, Paint Ind. Mag. 71(2), 11 (1956). See also Colour Index vol. 4 (3rd ed., 1971) p 4662. Use as catalyst: R. Uma, J. C. Kuriacose, Indian Chem. Manuf. 8, 11 (1970). Cytotoxic effects: V. Bianchi et al., Toxicology 17, 219 (1980).
Properties: Light to dark green, fine, hexagonal crystals. mp about 2435°. bp about 3000°. d25 5.22. Turns brown on heating but reverts to green color on cooling. Cryst Cr2O3 is extremely hard; will scratch quartz, topaz, zircon. Practically insol in water, alc, acetone. Slightly sol in acids, alkalies.
Melting point: mp about 2435°
Boiling point: bp about 3000°
Density: d25 5.22
CAUTION: Trivalent chromium may cause skin irritation: S. Fregert, H. Rorsman, Arch. Dermatol. 90, 4 (1964).
Use: In abrasives, refractory materials, electric semiconductors; as pigment, particularly in coloring glass; in alloys; printing fabrics and banknotes; as catalyst for organic and inorganic reactions.