Iodide ions treated with acidified silver nitrate yield which color precipitate?

• A. White precipitate
• B. Cream precipitate
• C. Yellow precipitate
• D. No precipitate

Answer: (C)

When you test for halide ions with silver nitrate that’s been acidified, you’re looking at what solid forms when Ag+ meets X−. Each halide forms a different silver halide that is insoluble, and the color of that precipitate varies. Chloride gives white silver chloride, bromide gives cream silver bromide, and iodide gives yellow silver iodide. Iodide produces a yellow precipitate because silver iodide is the least soluble of the three, so it forms a yellow solid more readily. The acidified conditions prevent other reactions (like forming silver carbonate) from muddying the result, so the color directly indicates iodide ions.