Reactions of halides and silver nitrateEdexcel A-Level Chemistry: Mind map

Exam questions on Reactions of halides and silver nitrate

1. A technician adds concentrated sulfuric acid, in a fume cupboard, to separate samples of solid sodium chloride, sodium bromide and sodium iodide.
   Hydrogen iodide reduces sulfuric acid to hydrogen sulfide, H₂S. Deduce the change in oxidation number of sulfur and write a balanced equation for the reaction, in which iodine is also formed.2 marks
2. A technician has three unlabelled aqueous solutions, each containing one of sodium chloride, sodium bromide and sodium iodide. She has dilute nitric acid, aqueous silver nitrate, dilute aqueous ammonia and concentrated aqueous ammonia.
   The precipitate formed in one solution is white and dissolves completely in dilute aqueous ammonia. Identify the halide ion present and give the formula of the ion that makes the precipitate dissolve.2 marks
3. A technician adds concentrated sulfuric acid to solid sodium chloride in a fume cupboard. She tests the steamy fumes with a glass rod dipped in concentrated ammonia solution and by bubbling them into water. She then repeats the experiment with solid sodium bromide, which also gives orange-brown fumes and a colourless gas with a choking smell.
   Explain the three observations made with sodium chloride, using equations where appropriate.3 marks