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

Jul 3, 2017

$\left[A g {\left(N {H}_{3}\right)}_{2}\right] C l \left(a q\right) + 2 H C l \left(a q\right) \rightarrow A g C l \left(s\right) \downarrow + 2 N {H}_{4}^{+} C {l}^{-} \left(a q\right)$

#### Explanation:

Silver ion can form a complex ion with ammonia to give ${\left[A g {\left(N {H}_{3}\right)}_{2}\right]}^{+}$. 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.

Jul 3, 2017

This is kind of an interesting reaction.

From the $\text{HCl}$, while the ${\text{Cl}}^{-}$ doesn't really do anything other than induce the common ion effect (the ${\text{Cl}}^{-}$ on the $\text{AgCl} \left(s\right)$ was from the outer coordination sphere of the complex), the ${\text{H}}^{+}$ 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 $\text{Ag}$ atom (which is fairly weak anyway) and form a stronger $\sigma$ bond to form the weak acid, ${\text{NH}}_{4}^{+}$.