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Test for halogenated compounds with silver nitrate solution. The three test tubes show the result of adding silver nitrate solution to (left to right): chloroethane, bromoethane and iodoethane. In each case the halogen (chlorine, iodine, bromine) atom reacts with the silver ion and the corresponding silver halide forms. The colour and solubility of the silver halide varies depending on the halogen and the solvent. Here, in dilute ammonia solution, silver chloride is soluble, silver bromide is an off-white precipitate and silver iodide is a light cream precipitate. Concentrated ammonia solubility tests can help distinguish bromides and iodides. (KEYSTONE/SCIENCE PHOTO LIBRARY/ANDREW LAMBERT PHOTOGRAPHY)