The flame test of identification of cations

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 The flame test of identification of cations



What is the flame test of identification of cations


The flame test of identification of cations is a test that helps to identify certain cations. It is a qualitative analysis technique that is used in chemistry. (Specially in inorganic chemistry) This test reveals the iconic identity of certain cations.


  • In this test the flame reveals iconic identity of the relevant cation.


  • The flame test is not applicable for some cations like magnesium (Mg) and zinc (Zn).
  • This is because magnesium and zing does not produce unique or distinct colours.



The procedure


  1. First step is to create a metal ion sample. This can be either a solution of the specific ion or solid salt.


  1. Next step is to use something like a platinum rod / loop, nichrome rod / loop or a graphite rod and dip it into the sample (salt solution or the solid salt.)


  1. Then the dipped rod or the loop should be held in the non-luminous part of the Bunsen burner. So the distinct colour of the relevant cation can be observed.



Colours of some popular cations


  • Li+ (Lithium) - Red / Crimson red
  • Na+ (Sodium) - Yellow
  • K+ (Potassium) - Lavender / Lilac
  • Ca2+ (Calcium) - Brick red / Orange-red
  • Sr2+ (Strontium) - Crimson red
  • Rb+ (Rubidium) - Violet red
  • Ba2+ (Barium) - Apple green
  • Cs+ (Cesium) - Blue
  • Cu2+ (Copper) - Green / Blue-green 
  • Mn2+ (Manganese) - Yellowish green
  • Fe3+ (Ferric / Iron(III)) - Orange-brown