Question

What is the equation for: Hydrochloric acid is added to diammine silver (l) chloride?

Answer 1

`[Ag(NH_3)_2]Cl(aq) + 2HCl(aq) rarr AgCl(s)darr + 2NH_4^+Cl^(-)(aq)`

Explanation:

Silver ion can form a complex ion with ammonia to give `[Ag(NH_3)_2]^+`. The addition of hydrochloric acid would protonate the amine, decompose the complex ion, and cause precipitation of the highly insoluble silver halide as a curdy white precipitate.

Answer 2

This is kind of an interesting reaction.

From the `"HCl"`, while the `"Cl"^(-)` doesn't really do anything other than induce the common ion effect (the `"Cl"^(-)` on the `"AgCl"(s)` was from the outer coordination sphere of the complex), the `"H"^(+)` can protonate the ammine ligands in the inner coordination sphere:

`["Ag"("NH"_3)_2]"Cl"(aq) + 2"HCl"(aq) -> "AgCl"(s) + 2"NH"_4"Cl"(aq)`

This works since the ammine ligands are Lewis bases. They can break their `sigma` interaction with the `"Ag"` atom (which is fairly weak anyway) and form a stronger `sigma` bond to form the weak acid, `"NH"_4^(+)`.