Title: Potassium Dichromate(VI)
CAS Registry Number: 7778-50-9
Additional Names: Potassium bichromate
Molecular Formula: Cr2K2O7
Molecular Weight: 294.18
Percent Composition: Cr 35.35%, K 26.58%, O 38.07%
Line Formula: K2Cr2O7
Literature References: In the U.S.A. it is usually prepared by the reaction of potassium chloride on sodium dichromate: Vetter in Kirk-Othmer Encyclopedia of Chemical Technology vol. 3 (Interscience, New York, 1949) p 951; Hartford, Copson, ibid. vol. 5 (2nd ed., 1964) pp 484-488. In Germany it is obtained from potassium chromate produced by roasting the chrome ore with KOH. Ref: Müller, Glissmann in Ullmanns Encyklopädie der technischen Chemie vol. 5 (Munich, 3rd ed., 1954) p 580.
Properties: Bright orange-red crystals. Not hygroscopic or deliquescent (difference from sodium dichromate). Crystal habit: prismatic. Crystal system: triclinic pinacoidal, transition to monoclinic at 241.6°. d425 2.676. Bulk density: 100 lbs/cu ft. mp 398°. Dec at about 500°. Heat of fusion 29.8 cal/g. Heat of soln -62.5 cal/g. Specific heat 0.186 at 16° -98°. Soluble in water. A satd aq soln contains at 0°: 4.3%, at 20°: 11.7%, at 40°: 20.9%, at 60°: 31.3%, at 80°: 42.0%, at 100°: 50.2%. Acid reaction: A 1% aq soln has a pH of 4.04 and a 10% soln has a pH of 3.57.
Melting point: mp 398°
Density: d425 2.676
CAUTION: Intern. a corrosive poison. Industrial contact may result in ulceration of hands, destruction of mucous membranes and perforation of nasal septum. See E. Browning, Toxicity of Industrial Metals (Appleton-Century Crofts, New York, 2nd ed., 1969) pp 119-131. See also Chromium.
Use: In tanning leather, dyeing, painting, decorating porcelain, printing, photolithography, pigment-prints, staining wood, pyrotechnics, safety matches; for bleaching palm oil, wax, and sponges; waterproofing fabrics; as oxidizer in the manuf of organic chemicals; in electric batteries; as depolarizer for dry cells. As corrosion inhibitor in preference to sodium dichromate where lower soly is advantageous. Pharmaceutic aid (oxidizing agent).
Therap-Cat-Vet: Caustic. |