Question

Aqueous ammonia is added to a mixture of silver chloride and water. Given that Kf for the reaction between Ag+ and NH3 is large, which of the following are true?

A) The free ions are favored over the complex ion.
B) The complex ion is favored over solid silver chloride.
C) The free Ag+ ion is unstable.
D) More silver chloride will precipitate.

Answer 1

B) The complex ion is favored over solid silver chloride

C) The free Ag+ ion is unstable.

Step-by-step explanation:

Hello,

In this case, since the dissociation of solid silver chloride occurs at equilibrium with a neglectable solubility product (very small Ksp), which means that the solid tends to remain undissolved:

`AgCl(s)\rightleftharpoons Ag^+(aq)+Cl^-(aq)`

By the addition of ammonia, the following reaction is favored:

`Ag^+(aq)+2NH_3(aq)\rightleftharpoons [Ag(NH_3)_2]^+(aq)`

Which has a large equilibrium constant, which means that the formation of the complex is assured. In such a way, by addition of more ammonia, more complex will be formed, therefore B) The complex ion is favored over solid silver chloride is true. Moreover, C) The free Ag+ ion is unstable, since they tend to form the complex once they are formed by the solid silver chloride so it readily reacts.

Best regards.