flame tests

Flame tests can be used to inventory some metal ions ( cations). Lithium, sodium, potassium, calcium and copper compounds produce distinctive colours in flame tests

Method:

  1. Place a nichrome wire into the roaring flame of a Bunsen burner to sterilise and remove and remains from previous tests

  2. Then, dip the clean nichrome wire into the solution

  3. Place the wire into the roaring flame of a Bunsen burner and note observations

If the ionic bond contains the following metal ions ( cations ) it will turn the corresponding colours:

Lithium - crimson

Sodium - orange

Potassium - lilac

Calcium - orange/red

Copper - green

Problems with this test

There are three main problems with the flame test;

  • two results give a red flame and two results that give an orange flame ( this can be solved by further testing )

  • Colours may be subjective

  • If the substance contains two metals you would not be able to see both colours