Example Question - 2

Question: Describe how acidified silver nitrate solution and ammonia solution can be used to identify chloride, bromide and iodide ions.First add dilute nitric acid. This removes carbonate or hydroxide ions, which would also form a precipitate with silver ions and give a false result. Hydrochloric acid cannot be used because it contains chloride ions.Then add silver nitrate solution. Chloride gives a white precipitate of AgCl, bromide gives a cream precipitate of AgBr and iodide gives a yellow precipitate of AgI. The ionic equation is Ag⁺(aq) + X^-(aq) → AgX(s).The colours can be hard to tell apart, so ammonia solution is added. AgCl dissolves in dilute ammonia, AgBr dissolves only in concentrated ammonia and AgI does not dissolve in concentrated ammonia.