Chromium(III) chloride

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Chromium(III) chloride
Names
IUPAC name
Chromium(III) chloride
Other names
Chromic chloride
Chromium trichloride
Properties
CrCl3
Molar mass 158.36 g/mol (anhydrous)
266.45 g/mol (hexahydrate)
Appearance Purple (anhydrous)
Dark green (hexahydrate)
Odor Odorless
Density 2.87 g/cm3 (anhydrous)
1.76 g/cm3 (hexahydrate)
Melting point 1,152 °C (2,106 °F; 1,425 K) (anhydrous)
83 °C (181 °F; 356 K) (hexahydrate)
Boiling point 1,300 °C (2,370 °F; 1,570 K) (decomposes)
anhydrous
Almost insoluble
hexahydrate
58.5 g/100 ml (20 °C)
Solubility Insoluble in acetone, diethyl ether, ethanol
Hazards
Safety data sheet Sigma-Aldrich (anhydrous)
Sigma-Aldrich (hexahydrate)
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
1,870 mg/kg (rat, oral)
Related compounds
Related compounds
Iron(III) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Chromium(III) chloride (CrCl3) is a compound of chromium. It is available in two forms, anhydrous and hydrated.

Properties

Chemical

Chromium(III) chloride will react with bases to give chromium hydroxide.

Physical

Chromium(III) chloride is a purple (anhydrous) or dark green (hydrated) solid.

Availability

Chromium chloride is sold by chemical suppliers.

Preparation

Chromium chloride hexahydrate can be obtained by reacting chromium oxide, hydroxide or plain chromium metal with conc. hydrochloric acid.

Chromium chloride anhydrous can be prepared by reacting chromates, chromium(III) oxide or just chromium metal with hydrochloric acid in methanol.

A more energetic route involves the carbothermic chlorination of chromium(III) oxide between 650–800 °C.

Reacting chlorine gas with hot chromium metal will also give anhydrous CrCl3.

Heating chromium(III) chloride hexahydrate in air will cause some of it to oxidize, resulting in CrCl3 contaminated with oxide and oxychloride. To obtain the anhydrous form from the hexahydrate, you must heat the CrCl3 in the presence of a chlorine or chloride source, like thionyl chloride or dry hydrogen chloride gas.

Projects

  • Make chromates and dichromates
  • Make chromium(II) chloride
  • Make Cr coordination complexes and adducts
  • Make organochromium compounds

Handling

Safety

While less toxic than Cr(VI) compounds, chromium chloride is less toxic, although it's still quite harmful.

Storage

In closed bottles, air-tight for the anhydrous form.

Disposal

Should be converted to less soluble forms and sent to disposal facilities. You can also recycle it.

References

Relevant Sciencemadness threads