Question

Which is more likely to dissolve in an acidic solution, silver sulfide or silver chloride? Why?

Short answer

Silver sulfide dissolves readily in the acidic solution.

Step-by-step solution

Definition of acidic solution

Any aqueous solution which has a $\text{pH}$less than$7$ is defined as an acidic solution.

Find which salt dissolves more likely in an acidic solution

Silver sulfide and silver chloride are precipitates and partially dissolve in aqueous media.

$\begin{array}{l}\text{AgS(s)}\rightleftharpoons {\text{Ag}}^{\text{+}}\text{(aq)}+{\text{S}}^{\text{2-}}\text{(aq)}\\ \text{AgCl(s)}\rightleftharpoons {\text{Ag}}^{\text{+}}\text{(aq)}+{\text{S}}^{\text{2-}}\text{(aq)}\end{array}$

In acidic solution, ${\text{H}}^{\text{+}}$concentration is high. Protons have a greater affinity for sulfide than chloride because sulfide is a stronger conjugate base than chloride. So, protons bind with sulfide ions and form hydrogen sulfide.

When the concentration of sulfide ions decreases, the equilibrium shifts to the right to produce more sulfide ions. So silver sulfide dissolves more in acidic solution than silver chloride.