Final answer:
Adding solid AgCl to a saturated solution does not change the [Cl-], but adding NH3(aq) does increase [Cl-] by forming a complex ion with Ag+ and promoting further dissolution of AgCl.
Step-by-step explanation:
The question asks which of the following will increase the concentration of chloride ions ([Cl-]) in a saturated chloride solution: the addition of AgCl(s) or the addition of NH3(aq). When AgCl is added to an already saturated solution, it will not dissolve further because the solution has reached its maximum solubility limit for that compound. Therefore, adding more solid AgCl does not increase the [Cl-] in the solution.
On the other hand, the addition of NH3(aq) can increase the solubility of AgCl by forming a complex ion with the silver ions (Ag+). This reaction reduces the concentration of free Ag+ ions available to combine with Cl- ions, thus driving the dissolution of additional AgCl in order to re-establish equilibrium. Consequently, more AgCl dissolves, thereby increasing the concentration of Cl- ions in the solution.