The chromium atoms are in oxidation state +6 in both, and the chromate and dichromate ions are fairly strong oxidizing agents. Chromium in the +6 (or VI) oxidation state is often referred to as hexavalent chromium.
In an aqueous solution, chromate and dichromate anions are in a chemical equilibrium.
2 CrO42− + 2 H3O+ Cr2O72− + 3 H2O
Barium Chromate
Barium chromate (or barium chromate oxide or chromic acid barium) is a fine light yellow powder with the formula BaCrO4. It is very insoluble in water, but is soluble in acids:
2 BaCrO4 + 2 H+ → 2 Ba2+ + Cr2O72- + H2O
Copper Chromate
We are currently having the exterior of some copper coils finished with Luster-On Cobra C conversion coating to prevent cosmetic discoloration during humidity exposure. Does anyone know of any military/commercial/industrial specifications - along the lines of ASTM B912 or Mil-C-5541 - that could be called out on our part drawings to specify this finish.
