Final answer:
In a saturated solution of AgCN, the concentration of CN- is the highest because it is present as a free ion and also part of the Ag(CN)₂⁻ complex. The correct order of concentrations is [CN-] > [Ag(CN)₂⁻] > [Ag+]. The correct option is D.
Step-by-step explanation:
The question at hand involves determining the concentrations of Ag+, CN-, and Ag(CN)₂⁻ in a saturated solution of AgCN. The reaction of Ag+ with CN- goes to completion, forming the Ag(CN)₂⁻ complex. Once the formation of this complex is complete, any additional Ag+ will result in the precipitation of AgCN.
Regarding the titration of cyanide ion with AgNO3, the amount of Ag+ that reacted with the CN- present in the original sample can be used to determine the mass of NaCN present. The concentrations of these species in a saturated solution are dictated by the solubility product constant (Ksp) of AgCN and the formation constant (Kf) of the Ag(CN)₂⁻ complex.
In such a solution, CN- concentration is typically the highest because it comes both from the dissociation of AgCN and from the complexing with Ag+ to form Ag(CN)₂⁻. Therefore, [CN-] > [Ag(CN)₂⁻] > [Ag+], which corresponds to the fact that the CN- is acting both as a ligand to form the complex as well as being present as a free ion. Hence, option (d) [CN-] > [Ag(CN)₂⁻] > [Ag+] is the correct answer.