In the course of various qualitative analysis procedures, the following mixtures are encountered: (a) Zn²⁺ and Cd²⁺. Suggest how each mixture might be separated.

Verified step by step guidance

1. Identify the chemical properties of Zn^{2+} and Cd^{2+} ions, such as their solubility in different reagents.
2. Consider using a reagent that forms a precipitate with one ion but not the other. For example, sulfide ions (S^{2-}) can be used to precipitate CdS, which is insoluble, while ZnS is more soluble in acidic conditions.
3. Add a dilute acid to the mixture to ensure that ZnS remains dissolved while CdS precipitates out.
4. Filter the mixture to separate the solid CdS from the solution containing Zn^{2+}.
5. Wash and dry the precipitate to obtain pure CdS, and the remaining solution will contain Zn^{2+} ions.

Key Concepts

Solubility and Precipitation Reactions

Solubility refers to the ability of a substance to dissolve in a solvent, while precipitation reactions occur when two soluble salts react to form an insoluble compound. Understanding these concepts is crucial for separating ions in a mixture, as selective precipitation can be used to isolate specific ions based on their differing solubilities.

Complex Ion Formation

Complex ion formation involves the interaction of metal ions with ligands to form a stable complex. This concept is essential for separating metal ions like Zn²⁺ and Cd²⁺, as specific ligands can selectively bind to one metal ion over the other, allowing for their separation through techniques such as extraction or chromatography.

Ion Selectivity and Chromatography

Ion selectivity refers to the ability to preferentially separate ions based on their chemical properties. Chromatography is a technique that exploits these differences, allowing for the separation of Zn²⁺ and Cd²⁺ by passing the mixture through a medium that interacts differently with each ion, thus achieving separation based on their affinities.