Flame Tests | Chemistry for Grade 10 PDF Download

About Flame Tests

• Metal ions produce a colour if heated strongly in a flame
• Ions from different metals produce different colours
• The flame test is thus used to identify metal ions by the colour of the flame they produce
• Dip the loop of an unreactive metal wire such as nichrome or platinum in dilute acid, and then hold it in the blue flame of a Bunsen burner until there is no colour change
• This cleans the wire loop and avoids contamination
• This is an important step as the test will only work if there is just one type of ion present
• Two or more ions means the colours will mix, making identification erroneous
• Dip the loop into the solid sample and place it in the edge of the blue Bunsen flame
• Avoid letting the wire get so hot that it glows red otherwise this can be confused with a flame colour

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 Tip

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