Transition metal solutions. Beakers with solutions of transition metal salts. Compounds containing transition metals are often coloured. Left to right: chromium (III) potassium sulphate (KCr (SO4)2, blue), ammonium metavanadate (V) (NH4VO3, yellow), cobalt chloride (CoCl2, rose-red), potassium dichromate (VI) (K2Cr2O7, orange-red), nickel sulphate (NiSO4, green-blue), potassium permanganate (KMnO4, magenta-violet), iron (III) chloride (FeCl3, brown-yellow), copper sulphate (CuSO4, blue), potassium chromate (VI) (K2CrO4, yellow). |