Potassium dichromate

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MFA Acc. #: 2003.166

Description

Bright orange crystals that are light sensitive. Potassium dichromate is used as a chrome mordant in dyeing textiles. It is also used to chrome tan leather and stain wood to an orange color. Potassium dichromate is used as an intensifier in black and white photographic processing. It is used as a pigment and as an insecticide. Potassium dichromate may also be used as a colorimetric reagent for the detection of lead in objects because the two materials react to form bright yellow lead chromate crystals (Odegaard et al 2000). Silver reacts with potassium dichromate to form a red precipitate.

Synonyms and Related Terms

potassium bichromate; red potassium chromate; red potassium chromate; dipotassium dichromate

Chemical structure

Potassium dichromate.jpg


Other Properties

Soluble in water. Insoluble in ethanol.

Composition K2Cr2O7
CAS 7778-50-9
Melting Point 396
Density 2.676
Molecular Weight mol. wt. = 294.18
Refractive Index 1.7202, 1.7380, 1.8197
Boiling Point 500 (dec)

Hazards and Safety

Toxic by ingestion or inhalation. Severely corrosive on contact with hands. Strong oxidizing agent.

Mallinckrodt Baker: MSDS

Additional Information

N.Odegaard, S.Carroll, W.Zimmt, Material Characterization Tests for Objects of Art and Archaeology Archetype Publications, London, 2000, lead p. 70, silver p.82-84.

Sources Checked for Data in Record

  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • Palmy Weigle, Ancient Dyes for Modern Weavers, Watson-Guptill Publications, New York, 1974
  • Tom Rowland, Noel Riley, A-Z Guide to Cleaning, Conserving and Repairing Antiques, Constable and Co., Ltd., London, 1981
  • Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
  • John and Margaret Cannon, Dye Plants and Dyeing, Herbert Press, London, 1994
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 7790
  • N.Odegaard, S.Carroll, W.Zimmt, Material Characterization Tests for Objects of Art and Archaeology, Archetype Publications, London, 2000
  • CRC Handbook of Chemistry and Physics, Robert Weast (ed.), CRC Press, Boca Raton, Florida, v. 61, 1980 Comment: ref. index=1.7202, 1.7380, 1.8197

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