Dichromate, in aqueous solution

The me.thods for the preparation of potassium mono-chlorochromate include the action of hydrochloric acid on potassium dichromate in aqueous solution/ the reaction of potassium chloride with chromium(VI) oxide in aqueous solution and the action of chromyl chloride on potassium chromate dissolved in water or glacial acetic acid. The last method is to be preferred, since it gives a good yield of the monochlorochromate of a fair degree of pimity. With the first or second method, the product often contains some greenish impurities. These impurities are probably produced by reduction of some of the chromate by hydrochloric add. 

Example 1 Influence of Temperature (-35 °C to 0 °C) on the Synthesis of HCl-Doped PANI with Sodium Dichromate in Aqueous Solution... 

Reduction of a dichromate in aqueous solution produces chromium(III) ion, Cr+ (really the hexahydrated ion, [Cr(H20)6] ), which has a violet color. The salts of this ion are similar in formula to those of aluminum. Chrome alum, KCr(S04)2 I2H2O, forms large violet octahedral crystals. 

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