# Chemical equilibrium system and where my ions went

1. May 27, 2009

### allywallyrus

sorry if this has been asked before, i did a search and couldnt find any results.
Explain fully what happens when $$H^+$$ is added to a mixture containing $$BaCrO_4(s)$$ and $$CrO_4^2^-$$.

The overall equation of ions in this experiment is $$H^+(aq)~+~2CrO_4^2^-\rightleftharpoons~Cr_2O_7^2^-(aq)~+~OH^-(aq)$$

when HCl is added to a solution of K2CrO4 and NaOH and Ba(NO3)2, the precipitate dissolves and the solution becomes orange. im pretty stumped, but im assuming K2CrO7 is present because it is orange in colour and that the precipitate from before becomes aqueous again but im not sure what the percipitate is (possibly Ba(OH)2??) or what is involved in the reaction. any push in the right direction is very appreciated!

2. May 27, 2009

### chemisttree

Ksp of barium hydroxide is 5 X 10-3 and the Ksp of barium chromate is 2.2 X 10-10.

Hope it helps.

3. May 27, 2009

### allywallyrus

i just realized i even identified barium chromate as a solid in my first post, hahaha :P
thank you anyway

so now my equation is looking more like HCl(aq) + BaCrO4 -> Cr2O7 + BaCl(aq) + H+

4. May 27, 2009

### Staff: Mentor

It won't work this way. Think what will happen to produced OH- in the presence of H+.

5. May 27, 2009

### allywallyrus

so we'd have H2O in the products instead, which makes more sense because this also balances nicely as well
i think this clears up where H+ ions were going, thanks :)

i dont suppose it would be a problem if i recycled this thread for questions on the same subject? i will probably have some more

6. May 27, 2009