Anhydrous chromium (3) chloride dissolve to a small extent in pure water but readily when small amount of chromium (2) is added
Answers
Chromium(II) chloride describes inorganic compounds with the formula CrCl2(H2O)n. The anhydrous solid is white when pure, however commercial samples are often grey or green; it is hygroscopic and readily dissolves in water to give bright blue air-sensitive solutions of the tetrahydrate Cr(H2O)4Cl2. Chromium(II) chloride has no commercial uses but is used on a laboratory-scale for the synthesis of other chromium complexes.
CrCl2 is produced by reducing chromium(III) chloride either with hydrogen at 500 °C:
2 CrCl3 + H2 → 2 CrCl2 + 2 HCl
or by electrolysis.[6]
Small scale preparations can use LiAlH4, Zinc or related reagents, to reduce CrCl3
4 CrCl3 + LiAlH4 → 4 CrCl2 + LiCl + AlCl3 + 2 H2
2 CrCl3 + Zn → 2 CrCl2 + ZnCl2
CrCl2 can also be prepared by treating a solution of chromium(II) acetate with hydrogen chloride.[7]
Cr2(OAc)4 + 4 HCl → 2 CrCl2 + 4 AcOH