In this video, Paul Cook demonstrates how to perform a classic flame test using a spray bottle. This qualitative analytical technique is employed to identify certain elements present in a sample by observing the characteristic colours produced when the sample is introduced into a flame. In this version, alcohol (IDA/IMS only) is added to a series of spray bottles containing metal salts and boric acid. The vapour is ignited and coloured flames are observed.
When specific elements are heated in a flame, the electrons within their atoms become excited and move to higher energy levels. As these electrons return to their ground state, they emit light at precise wavelengths, corresponding to various colours.
The flame test proves particularly useful for the identification of metal ions in the GCSE Chemistry curriculum, as they typically yield easily distinguishable colours. However, it’s important to note that relying solely on the flame test might not be adequate for definitively identifying all elements, as certain elements may display similar colours. Typically, this test is used as a preliminary screening method or in conjunction with other analytical techniques to achieve more comprehensive identification.
The flame colour emitted is specific to the metal ion salt.
Lithium – Red
Potassium – Lilac
Copper – Apple Green
Sodium – Orange
Strontium – Red
You will need:
All health and safety measures are the responsibility of the teacher doing the demonstration. A thorough risk assessment should be carried out and guidance procedures followed. It is suggested that you practice before demonstration in front of a class.
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