Which chemical is used to produce a positive confirmatory test for the presence of silver ions (Ag^+)?

• A. Chloride ions (Cl^-), typically added as hydrochloric acid
• B. Ammonium ions (NH_4^+), typically added as ammonium chloride
• C. Sulfate ions (SO_4^{2-}), typically added as sulfuric acid
• D. Nitrate ions (NO_3^-), typically added as nitric acid

Answer: (A)

Verified step by step guidance

1. Understand that a confirmatory test for silver ions (Ag^+) involves adding a reagent that reacts specifically with Ag^+ to form a distinctive precipitate or color change.
2. Recall that silver ions (Ag^+) react with chloride ions (Cl^-) to form silver chloride (AgCl), which is a white precipitate that is insoluble in water and serves as a positive test.
3. Write the chemical reaction for the confirmatory test: \(\mathrm{Ag^+ (aq) + Cl^- (aq) \rightarrow AgCl (s)}\) where \(AgCl\) is the white precipitate indicating the presence of silver ions.
4. Note that chloride ions are commonly introduced using hydrochloric acid (HCl) because it dissociates completely in water to provide \(Cl^-\) ions.
5. Recognize that other ions listed (ammonium, sulfate, nitrate) do not form a distinctive precipitate with silver ions under normal test conditions, so they are not used for this confirmatory test.