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Chromium(III) sulfate

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Chromium(III) sulfate
Names
IUPAC name Chromium(III) sulfate
Other names Basic chromium sulfate, chromic sulfate
Identifiers
CAS Number
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.030.217 Edit this at Wikidata
EC Number
  • 233-253-2
PubChem CID
UNII
UN number 2240 3077
CompTox Dashboard (EPA)
InChI
  • InChI=1S/2Cr.3H2O4S.12H2O/c;;3*1-5(2,3)4;;;;;;;;;;;;/h;;3*(H2,1,2,3,4);12*1H2/q2*+3;;;;;;;;;;;;;;;/p-6Key: ANNXSSGQVXBUEI-UHFFFAOYSA-H
  • InChI=1/2Cr.3H2O4S.12H2O/c;;3*1-5(2,3)4;;;;;;;;;;;;/h;;3*(H2,1,2,3,4);12*1H2/q2*+3;;;;;;;;;;;;;;;/p-6Key: ANNXSSGQVXBUEI-CYFPFDDLAL
SMILES
  • anhydrous: ..S(=O)(=O).S()(=O)=O.S()(=O)=O
  • dodecahydrate: ()()()().()()()().S(=O)(=O).S()(=O)=O.S()(=O)=O
Properties
Chemical formula Cr2(SO4)3 • 12H2O
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/cm (anhydrous)
1.86 g/cm (pentadecahydrate)
1.709 g/cm (octadecahydrate)
Melting point 90 °C
Boiling point >700 °C (decomposes to chromic acid)
Solubility in water insoluble (anhydrous)
soluble (hydrated)
Solubility soluble in alcohol
practically insoluble in acid
Magnetic susceptibility (χ) +11,800·10 cm/mol
Hazards
GHS labelling:
Pictograms GHS05: CorrosiveGHS07: Exclamation markGHS08: Health hazardGHS09: Environmental hazard
Signal word Warning
Hazard statements H314, H317, H332, H334, H335, H340, H350, H373, H412
Precautionary statements P201, P202, P260, P261, P264, P271, P272, P273, P280, P281, P285, P301+P330+P331, P302+P352, P303+P361+P353, P304+P312, P304+P340, P304+P341, P305+P351+P338, P308+P313, P310, P312, P314, P321, P333+P313, P342+P311, P363, P403+P233, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1 0 0
Flash point Non-flammable
NIOSH (US health exposure limits):
PEL (Permissible) TWA 1 mg/m
REL (Recommended) TWA 0.5 mg/m
IDLH (Immediate danger) 250 mg/m
Safety data sheet (SDS) MSDS
Related compounds
Other cations Aluminium sulfate
Related double salts Chrome alum
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). ☒N verify (what is  ?) Infobox references
Chemical compound

Chromium(III) sulfate usually refers to the inorganic compounds with the formula Cr2(SO4)3x(H2O), where x can range from 0 to 18. Additionally, ill-defined but commercially important "basic chromium sulfates" are known. These salts are usually either violet or green solids that are soluble in water. It is commonly used in tanning leather.

Chromium(III) sulfates

Three chromium(III) sulfates are well characterized:

  • Anhydrous chromium(III) sulfate, Cr2(SO4)3, (CAS #10101-53-8) is a violet solid that dissolves in water upon addition of a reducing agent.
  • Hydrated chromium(III) sulfate, Cr2(SO4)3·18H2O, (CAS #13520-66-6) is a violet solid that readily dissolves in water to give the metal aquo complex, . The formula of this compound can be written more descriptively as 2(SO4)3·6H2O. Six of the eighteen water molecules in this formula unit are water of crystallization.
  • Hydrated chromium(III) sulfate, Cr2(SO4)3·15(H2O), (CAS #10031-37-5) is a green solid that also readily dissolves in water. It is obtained by heating the 18-hydrate material above 70 °C. Further heating yields the anhydrous sulfate.

A variety of other chromium(III) sulfates are known, but also contain hydroxide or oxide ligands. Most important commercially is basic chromium sulfate, which is thought to be SO4 (CAS#39380-78-4). It results from the partial neutralization of the hexahydrates. Other chromium(III) hydroxides have been reported.

Structure of solid Cr(SO4)(H2O)(OH), showing the CrO6 coordination sphere typical of many chromium(III) compounds. Color code: red = O, yellow = S, dark blue = Cr.

Production

Chromium(III) sulfate are commonly obtained from the wastes of chromate oxidations of various organic compounds. Anthraquinone and quinone are produced on large scale by the x treatment of respectively anthracene and phenol with chromic acid. A chromium(III) oxide byproduct is generated, which is readily extracted into sulfuric acid. Evaporation of these acidic solutions affords salts if hydrate chromium(III) sulfate. Extraction of chromite ore with sulfuric acid in the presence of some chromate gives solutions of chromium(III) sulfate contaminated with other metal ions. Similarly, dissolution of chrome alloys gives chromium(III) sulfate together with ferrous sulfate.

Basic chromium(III) sulfate

Basic chromium sulfate is produced from chromate salts by reduction with sulfur dioxide, although other methods exist. The reduction could formally be written:

Na2Cr2O7 + 3 SO2 + H2O → Cr2(SO4)3 + 2 NaOH

Since 33% of the anion charges are due to hydroxy ions the basicity is 33% (but in tanning jargon it is known as 33% reduced). Products with higher basicities, e.g. 42% or 50% may be obtained by the addition of sodium carbonate, these are often used in combination with sodium formate. The sodium sulfate is often left in the technical product since it is inert with respect to the tanning process.

Natural occurrence

Three complex minerals that are in part Cr(III) sulfates: bentorite, reddingtonite, and putnisite.

References

  1. ^ NIOSH Pocket Guide to Chemical Hazards. "#0141". National Institute for Occupational Safety and Health (NIOSH).
  2. Covington, A. D.; Lampard, G. S.; Menderes, O.; Chadwick, A. V.; Rafeletos, G.; O'Brien, P. "Extended X-ray absorption fine structure studies of the role of chromium in leather tanning" Polyhedron 2001, volume 20, 461–466. doi:10.1016/S0277-5387(00)00611-2
  3. Riou, A.; Bonnin, A. (1982). "Structure de l'Hydroxysulfate de Chrome monohydrate". Acta Crystallographica B. 24 (5): 1968–38. doi:10.1107/S0567740881005001.
  4. ^ Gerd Anger; Jost Halstenberg; Klaus Hochgeschwender; Christoph Scherhag; Ulrich Korallus; Herbert Knopf; Peter Schmidt; Manfred Ohlinger. "Chromium Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a07_067. ISBN 978-3-527-30673-2.
  5. CW Harland; J Simpson. "Chromium sulfate tanning powder" (PDF). Farmers Fertiliser Ltd - a subsidiary of Fernz Corporation Ltd. Archived from the original (PDF) on 2018-01-27. Retrieved 2016-08-04.
  6. "Bentorite".
  7. "Redingtonite".
  8. "Putnisite".
  9. "List of Minerals". 21 March 2011.
Chromium compounds
Chromium(0)
Organochromium(0) compounds
  • Cr(C6H6)2
  • CrC6H6(CO)3
    • Chromium(I)
    Organochromium(I) compounds
    Chromium(II)
    Organochromium(II) compounds
    Chromium(II, III)
    Chromium(III)
    Chromium(IV)
    Chromium(V)
    Chromium(VI)
    Polyatomic ion
    Compounds containing the sulfate group (SO2−4)
    H2SO4 He
    Li2SO4 BeSO4 B2S2O9
    -BO3
    +BO3     		esters
    ROSO−3
    (RO)2SO2
    +CO3
    +C2O4     		(NH4)2SO4
    [N2H5]HSO4
    (NH3OH)2SO4
    NOHSO4
    +NO3     		H2OSO4 +F Ne
    Na2SO4
    NaHSO4     		MgSO4 Al2(SO4)3
    Al2SO4(OAc)4     		Si +PO4 SO2−4
    HSO3HSO4
    (HSO4)2
    +SO3     		+Cl Ar
    K2SO4
    KHSO4     		CaSO4 Sc2(SO4)3 TiOSO4 VSO4
    V2(SO4)3
    VOSO4     		CrSO4
    Cr2(SO4)3     		MnSO4 FeSO4
    Fe2(SO4)3     		CoSO4
    Co2(SO4)3     		NiSO4
    Ni2(SO4)3     		CuSO4
    Cu2SO4
    SO4     		ZnSO4 Ga2(SO4)3 Ge(SO4)2 As +SeO3 +Br Kr
    RbHSO4
    Rb2SO4     		SrSO4 Y2(SO4)3 Zr(SO4)2 Nb2O2(SO4)3 MoO(SO4)2
    MoO2(SO4)     		Tc Ru(SO4)2 Rh2(SO4)3 PdSO4 Ag2SO4
    AgSO4     		CdSO4 In2(SO4)3 SnSO4
    Sn(SO4)2     		Sb2(SO4)3 TeOSO4 I2(SO4)3
    (IO)2SO4
    +IO3     		Xe
    Cs2SO4
    CsHSO4     		BaSO4 * Lu2(SO4)3 Hf(SO4)2 Ta WO(SO4)2 Re2O5(SO4)2 OsSO4
    Os2(SO4)3
    Os(SO4)2     		IrSO4
    Ir2(SO4)3     		Pt2(SO4)5 AuSO4
    Au2(SO4)3     		Hg2SO4
    HgSO4     		Tl2SO4
    Tl2(SO4)3     		PbSO4
    Pb(SO4)2     		Bi2(SO4)3 PoSO4
    Po(SO4)2     		At Rn
    Fr RaSO4 ** Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
     
    * La2(SO4)3 Ce2(SO4)3
    Ce(SO4)2     		Pr2(SO4)3 Nd2(SO4)3 Pm2(SO4)3 Sm2(SO4)3 EuSO4
    Eu2(SO4)3     		Gd2(SO4)3 Tb2(SO4)3 Dy2(SO4)3 Ho2(SO4)3 Er2(SO4)3 Tm2(SO4)3 Yb2(SO4)3
    ** Ac2(SO4)3 Th(SO4)2 Pa U2(SO4)3
    U(SO4)2
    UO2SO4     		Np(SO4)2 Pu(SO4)2 Am2(SO4)3 Cm2(SO4)3 Bk Cf2(SO4)3 Es Fm Md No
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