Nomenclature
CAS number: 10588-01-9
Chromic acid (H
2Cr
2O
7) sodium
salt (1:2); sodium bichromate; bichromate of soda.
Cr
2Na
2O
7; mol wt 261.97.
Cr 39.70%, Na 17.55%, O 42.75%.
Na
2Cr
2O
7.
Description and references
Usually prepd from Na2CrO4 and H2SO4. Description of industrial processes:
Müller, Glissmann in Ullmanns Encyklopdie
der technischen Chemie vol. 5 (Munich, 3rd
ed., 1954) p 575; Faith, Keyes & Clark's
Industrial Chemicals, F. A. Lowenheim, M. K. Moran, Eds.
(Wiley-Interscience, New York, 4th ed., 1975) pp 731-736.
Derivative
Dihydrate.
Nomenclature
CAS number: 7789-12-0
Cr
2Na
2O
7.2H
2O; mol wt 298.00.
Cr 34.90%, Na 15.43%, O 48.32%, H 1.35%.
Properties
Reddish to bright orange, somewhat deliquescent
crystals. Crystal system: monoclinic sphenoidal. Crystal habit:
elongated prismatic. d425 2.348. Bulk density: 96 lbs/cu ft. Becomes anhydr on prolonged
heating at ≈100°. The anhydr salt mp 356.7° and starts to dec at ≈400°. Heat
of soln 28.2 cal/g. Very sol in water. A satd aq soln contains
at 0°: 70.6% Na2Cr2O7.2H2O; at 20°: 73.18%; at 40°: 77.09%; at 60°: 82.04%; at 80°:
88.39%; at 100°: 91.43%. A 20% soln freezes at 3.5°, a 30% soln
at 6°, a 60% soln at 26°, a 69% soln at 48°. Specific heat of
20% soln at 25°: 0.85 cal/g/°C. Solns are acidic: pH of 1% soln:
4.0; pH of 10% soln: 3.5.Caution
Potential symptoms of overexposure
by ingestion are violent gasteroenteritis, peripheral vascular collapse,
vertigo, muscle cramps, coma, hemorrhagic diathesis, fever, liver
damage and acute renal failure. Direct contact may be highly corrosive
to skin and mucous membranes. See Clinical Toxicology of Commercial Products, R. E. Gosselin et al., Eds. (Williams & Wilkins, 5th ed., 1984) Section
II, p 108. Chromium hexavalent compounds are listed as known human
carcinogens: Report on Carcinogens, Eleventh
Edition (PB2005-104914, 2004) p III-63.Use
Oxidizing agent in manuf of dyes, many other synthetic
organic chemicals, inks, etc.; in chrome-tanning of hides; in electric
batteries; bleaching fats, oils, sponges, resins; refining petroleum;
manuf chromic acid, other chromates and chrome pigments; in corrosion-inhibitors,
corrosion-inhibiting paints; in many metal treatments; electroengraving
of copper; mordant in dyeing; for hardening gelatin; for the defoliation
of cotton plants and other plants and shrubs, La Lande,
US 2760854 (1956 to Pennsylvania Salt). Prepn of titrant in redox reactions.
Therapeutic Category
Anti-infective (topical).