Several reactions involving: Chromate and Dichromate ions

[Rainism]

I'm not sure what: BaCrO4(s) + HNO3(aq) would yield. Would the product of this reaction be:

Ba(NO3)2(aq) + H2CrO4(aq)?

Or,

Ba(NO3)2(aq) + H2O(l) + Cr2O7(aq) ?

If so, why is this?

 

[Borek]

In general barium chromate is considered to be soluble in acids (producing solution of dichromate), but details depend on the pH.

This is a multi stage equilibrium. In low pH CrO₄^2- gets protonated, so the barium chromate dissolves (although exact effect depends on the pH, and Ksp and Ka1 values). Then the chromic acid dimerizes - again, exact effect depends on the concentration of the chromate and on the pH (not to mention possible precipitation of a barium dichromate, and possible protonation of the dichromate anion). So there is plenty of reaction taking place at the same time.