Standard QA of Silver Chromate(VI) yields the following the result:
Yellow Precipitate formed upon addition of aq Silver Nitrate, soluble in Nitric Acid and Aq. NH3. I'm not sure why Ag2CrO4 formed dissolves in both HNO3 and NH3.
(1)- 2[CrO4]2- + 2H+ <-> [Cr2O7]2- + H2O
(2)- Ag2CrO4 (s) <-> 2Ag+ (aq) + CrO4^2- (aq)
I think addition of dil. HNO3 favours the forward the reaction of eqbm (1), thus reducing the availability of chromate(VI) ions in the solution, hence more silver chromate(VI) will dissolve, in accordance to Le Chaterlier's Principle acting in Eqbm(2).
In the case of solubility in ammonia, I think it's because of NH3's ability to form diamine silver complex.
Can someone enlighten me?