The reaction if Ba2+ + CrO42- is BaCrO4. Now how will the addition of HCl affect teh equilibrium?

Question

I believe that the equilibrium will not be affected, but I want to make sure.

Thanks

Answer 1

I am nearly certain that the HCL will not affect the outcome.

Answer 2

Lancenigo di Villorba (TV), Italy

I AGREE NOT WITH PRECEEDING ANSWER.
Why?
I thought cromate ions are derived by acid-base dissociation's equilibria of cromic acid (e.g. H2CrO4).
The latter show a chemical behaviour as strong acid.
On the other hand, cromic acid is a bi-basic acid, thus it dissociate itself into hydrogenocromate and cromate ions.
The latter two ions are bound by an acid-base chemical equilibrium. Obviously, this equilibrium is more important the greater are amount of the ions involved.
Hence, at the greatest acidity's grades (e.g. the lowest pH's conditions) you convert cromate ions into hydrogenocromate ones.
Since the latters cannot form few soluble barium's compound, you understood that hydrochloric acid's solutions may avoid barium's detection as cromate compound.

In effect, a classical essay for barium ions is "Caron-Raquet" 's reaction where potassium cromate and sodium acetate are dissolved in acetic acid's solutions...here is not involved hydrochloric acid.

I hope this helps you.

Answer 3

You need to be aware of the equilibrium:

2(CrO4)2- + 2H+ <-----> (Cr2O7)2- + H2O

If you increase the H+ ion concentration, you will convert most of the yellow chromate(VI) ions in solution to orange dichromate(VI) ions. You will lower the concentration of aqueous chromate so much that the precipitate of barium chromate will dissolve, to try to replace the aqueous ions that have been removed.

This is a typical exercise in Le Chatelier's Principle.