In which of the following solutions will AgCl be most soluble?

• A. A solution containing aqueous NH3
• B. Pure water
• C. A solution containing AgNO3
• D. A solution containing NaCl

Answer: (A)

Verified step by step guidance

1. Recall that the solubility of a salt like AgCl depends on the common ion effect and complex ion formation. AgCl dissociates as: \(\$AgCl_{(s)} \rightleftharpoons Ag^{+}_{(aq)} + Cl^{-}_{(aq)}\).
2. In pure water, AgCl dissolves to a limited extent based on its solubility product constant (\(K_{sp}\)), with no additional ions affecting the equilibrium.
3. In a solution containing AgNO\(_3\), there is an increase in \(Ag^{+}\) ions, which shifts the equilibrium to the left (Le Chatelier's principle), decreasing AgCl solubility due to the common ion effect.
4. In a solution containing NaCl, there is an increase in \(Cl^{-}\) ions, which also shifts the equilibrium to the left, decreasing AgCl solubility due to the common ion effect.
5. In a solution containing aqueous NH\(_3\), \(Ag^{+}\) ions form a complex ion with NH\(_3\) (e.g., \([Ag(NH_3)_2]^+\)), effectively removing free \(Ag^{+}\) ions from solution and shifting the equilibrium to the right, increasing AgCl solubility.