Identifying Metal Ions (Oxford AQA IGCSE Combined Science Double Award)

Identifying Metal Ions

• The flame test is used to identify the positive metal ion (cations) by the colour of the flame they produce

  • Ions from different metals produce different colours

• To carry out a flame test:

  • Dip the loop of an unreactive metal wire such as nichrome or platinum in dilute acid

  • Hold it in the blue flame of a Bunsen burner until there is no colour change

  • Dip the loop into the solid sample / solution and place it in the edge of the blue Bunsen flame

• It is important to place the wire into acid first to prevent contamination 

  • Not doing this might result in two or more ions being present on the wire meaning the colours will mix 

  • One colour could mask another colour and you will not be able to identify the ion

How to carry out a flame test

• The colour of the flame is observed and used to identify the metal ion present:

Flame Test Colours