Predict what will happen if nitric acid is added to a solution of [Ag(NH3)2]Cl in NH3 (aq) (Hints: (1) What other type of reaction happens ? (2) Use Le Chatalier Principle)

Answer 1

This is a complex ion problem, so we need to look at the formation of the complex ion as well as the reaction of this ion.

AgCl + 2NH₃ ⇄ [Ag(NH₃)₂]Cl ... formation

[Ag(NH₃)₂]Cl <==> AgCl + 2NH₃ ... dissociation (probably small if K_f is large)

[Ag(NH₃)₂]Cl(aq) + HNO₃(aq) ==> 2NH₄NO₃(aq) + AgCl(s)

Not sure why they want you to use Le Chatelier's Principle unless we know the Kf (formation constant) for the complex ion. Usually they are quite large, so would not come into play for the dissociation reaction. Addition of HNO3 will cause a precipitate of AgCl to form, thus pulling the reaction toward the products.