Cupric Dichromate, CuCr₂O₇.2H₂O

Cupric Dichromate, CuCr₂O₇.2H₂O, forms reddish-brown crystals on evaporation in the cold of a solution of cupric hydroxide in chromic acid. It becomes anhydrous at 100° C. It is deliquescent and soluble in water and alcohol. The aqueous solution on boiling yields the basic chromate. The following compounds have been prepared:

CuCr₂O₇.4NH₃.2H₂O; CuCr₂O₇.4(C₆H₅NH₂); CuCr₂O₇.4(C₅H₅N); CuCr₂O₇.2(NH₂.CH₂.CH₂.NH₂).

Copper trichrornate and tetrachrornate are also known.