In this video, Paul Cook shows you how to demonstrate a classic flame test which is a qualitative analytical technique used to identify certain elements present in a sample by observing the characteristic colours produced when the sample is introduced into a flame.
When certain elements are heated in a flame, the electrons in their atoms get excited to higher energy levels. As the electrons return to their ground state, they emit light at specific wavelengths, which correspond to different colours. In this test, alcohol (IDA/IMS only) is added to a series of borosilicate beakers or crystallizing dishes containing metal salts and boric acid. The vapour is ignited and coloured flames are observed.
The flame test is particularly useful for the identifying metal ions topic in GCSE Chemistry, as they tend to produce easily distinguishable colours. However, it is essential to note that the flame test alone may not be sufficient to identify all elements definitively, as some elements may exhibit similar colours. It is typically used as a preliminary test or in conjunction with other analytical methods for a 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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