How to Carry Out a Flame Test (Edexcel IGCSE Science)

Flame Tests

Spec point — 6.17

• 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

Diagram showing the technique for carrying out a flame test

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

Diagram showing the colours formed in the flame test for metal ions

Exam Hint The sample needs to be heated strongly, so the Bunsen burner flame should be on a blue flame.