Chromium(III) sulfate

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Chromium(III) sulfate
Chromium(III) sulfate.jpg
Identifiers
CAS number 10101-53-8 YesY
13520-66-6 (dodecahydrate)
PubChem 24930
ChemSpider 21241287
UNII Y0C99N5TMZ YesY
Jmol-3D images Image 1
Properties
Molecular formula H24Cr2S3O24
Molar mass 392.16 g/mol
608.363 g/mol (dodecahydrate)

716.45 g/mol (octadecahydrate)

Appearance reddish-brown crystals (anhydrous), purple crystals (hydrated)
Density 3.10 g/cm3 (anhydrous)
1.86 g/cm3 (pentadecahydrate)
1.709 g/cm3 (octadecahydrate)
Melting point 90 °C
Boiling point decomposes to chromic acid
Solubility in water insoluble (anhydrous)
soluble (hydrated)
Solubility soluble in alcohol
practically insoluble in acid
Hazards
MSDS MSDS
EU Index Not listed
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point Non-flammable
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Chromium(III) sulfate usually refers to the inorganic compound with the formula Cr2(SO4)3 • 12(H2O). This consists of the hydrated sulfate salt of the metal aquo complex with the formula [Cr(H2O)6]3+, which is responsible for the purple color of this salt. It is widely used in the tanning of leather, with associated environmental damage.[citation needed]

Properties[edit]

Heating chromium(III) sulfate leads to partial dehydration to give a hydrated green salt (CAS#15244-38-9) and eventually the anhydrous derivative (CAS#10101-53-8).

Production[edit]

Basic chromium sulfate is produced from chromate salts by reduction with sulfur dioxide, although other methods exist.[1] The hydrous form may be formed by the reaction of chromium(III) oxide and sulfuric acid.

Cr2O3 + 3 H2SO4 → Cr2(SO4)3 + 3 H2O

References[edit]

  1. ^ Gerd Anger, Jost Halstenberg, Klaus Hochgeschwender, Christoph Scherhag, Ulrich Korallus, Herbert Knopf, Peter Schmidt, Manfred Ohlinger (2005), "Chromium Compounds", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a07_067