![]() You need to be able to recall the qualitative tests for the presence of carbonate, halide and sulphate ions in solution. The required information is summarised in the table below. You need to be able to write balanced chemical equations for the formation of these metal hydroxides. Some metal ions form coloured precipitates of the corresponding metal hydroxide when sodium hydroxide solution is added. It is very important that the sample is pure otherwise the flame colour may be obscured by the presence of colours from other elements. The elements and corresponding flame test colours that you are required to know are listed below. The colour is in fact the combination of a number of different wavelengths. Some of the wavelengths of energy emitted are in the visible part of the electromagnetic spectrum and appear as a characteristic colour. When these “excited” electrons lose energy and fall down to a lower energy level they release energy in the form of electromagnetic radiation. Electrons in the metal gain energy and move to higher energy levels or orbitals. A small sample of the compound is heated in the blue Bunsen burner flame. The required information is summarised in the table below.įlame tests are used to confirm the presence of particular metal ions in a compound. There are a series of simple chemical tests for the presence of certain gases. ![]() ![]() Some of the chemical tests in the GCSE syllabus are not present at A Level, but any self-respecting A Level Chemistry student should know them all. At GCSE and A Level there are a series of chemical tests that you need to know. Before the invention of modern spectroscopic techniques such as mass spectrometry, the only way a chemist could determine the presence of a particular element or organic functional group was to carry out a chemical test and observe the results.
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