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Chromium trifluoride

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Title: Chromium trifluoride  
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Chromium trifluoride

Dangerous for the Environment (Nature) N|
Chromium trifluoride
Names
IUPAC name
Chromium(III) fluoride
Other names
Chromium trifluoride
Identifiers
 YesY
(trihydrate)
(tetrahydrate)
ChemSpider  YesY
Jmol-3D images Image
PubChem
RTECS number GB6125000
Properties
small=yes}}} }}} 0}}} 1=C|C} }}} 1=H|H} }}} 1=Ac|Ac} }}} 1=Ag|Ag} }}} 1=Al|Al} }}} 1=Am|Am} }}} 1=Ar|Ar} }}} 1=As|As} }}} 1=At|At} }}} 1=Au|Au} }}} 1=B|B} }}} 1=Ba|Ba} }}} 1=Be|Be} }}} 1=Bh|Bh} }}} 1=Bi|Bi} }}} 1=Bk|Bk} }}} 1=Br|Br} }}} 1=Ca|Ca} }}} 1=Cd|Cd} }}} 1=Ce|Ce} }}} 1=Cf|Cf} }}} 1=Cn|Cn} }}} 1=Cl|Cl} }}} 1=Cm|Cm} }}} 1=Co|Co} }}} 1=Cr|Cr} }}} 1=Cs|Cs} }}} 1=Cu|Cu} }}} 1=Db|Db} }}} 1=Ds|Ds} }}} 1=Dy|Dy} }}} 1=Er|Er} }}} 1=Es|Es} }}} 1=Eu|Eu} }}} 1=F|F} }}} 1=Fe|Fe} }}} 1=Fl|Fl} }}} 1=Fm|Fm} }}} 1=Fr|Fr} }}} 1=Ga|Ga} }}} 1=Gd|Gd} }}} 1=Ge|Ge} }}} 1=He|He} }}}}
Documentation

Appearance green crystalline solid
Density 3.8 g/cm3 (anhydrous)
2.2 g/cm3 (trihydrate)
Melting point 1,100 °C (2,010 °F; 1,370 K) (sublimes)
negligible (anhydrous)
sparingly soluble (trihydrate)
Solubility insoluble in alcohols
soluble in HF, HCl
Structure
Rhombohedral, hR24
R-3c, No. 167
Hazards
Lethal dose or concentration (LD, LC):
LD50 (Median dose)
150 mg/kg (guinea pig, oral)[1]
US health exposure limits (NIOSH):
PEL (Permissible)
TWA 1 mg/m3[2]
REL (Recommended)
TWA 0.5 mg/m3[2]
250 mg/m3[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 YesY  (: YesY/N?)

Chromium(III) fluoride is the name for the chemical formula CrF3 as well as several related hydrates. The compound CrF3 is a green crystalline solid that is insoluble in common solvents, but the coloured hydrates [Cr(H2O)6]F3 and [Cr(H2O)6]F3•3H2O are soluble in water. The trihydrate is green, and the hexahydrate is violet. The anhydrous form sublimes at 1100–1200 °C. Like almost all compounds of chromium(III), these compounds feature octahedral Cr centres. In the anhydrous form, the six coordination sites are occupied by fluoride ligands that bridge to adjacent Cr centres. In the hydrates, some or all of the fluoride ligands are replaced by water.[3]

Production

Chromium(III) fluoride is produced from the reaction of chromium(III) oxide and hydrofluoric acid:[4]

Cr2O3 + 6 HF + 9 H2O → 2 [Cr(H2O)6]F3

The anhydrous form is produced from hydrogen fluoride and chromic chloride:[5]

CrCl3 + 3 HF → CrF3 + 3 HCl

Uses

Chromium(III) fluoride is not heavily used, but finds some applications as a mordant in textiles and as a corrosion inhibitor.

References

  1. ^
  2. ^ a b c
  3. ^ F.H. Herbstein, M. Kapon and G.M. Reisner, "Crystal structures of chromium(III) fluoride trihydrate. Structural chemistry of hydrated transition metal fluorides. Thermal decomposition of chromium(III) fluoride nonhydrate" Zeitschrift für Kristallographie 1985, volume 171, pp. 209
  4. ^ Gerd Anger, Jost Halstenberg, Klaus Hochgeschwender, Christoph Scherhag, Ulrich Korallus, Herbert Knopf, Peter Schmidt, Manfred Ohlinger, "Chromium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.doi:10.1002/14356007.a07_067
  5. ^ Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.
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